View source for United States congressional apportionment

{{Use American English|date = March 2019}}
{{Short description|How 435 seats are distributed to 50 states}}
{{Use mdy dates|date = December 2022}}
[[File:House Seats by State 1789-2020 Census.png|upright=1.3|300px|thumb|Allocation of seats by state, as percentage of overall number of representatives in the House, 1789–2020 census]]

'''United States congressional apportionment''' is the process<ref name="Kristin D. Burnett">{{cite web |author=Kristin D. Burnett |url=https://www.census.gov/prod/cen2010/briefs/c2010br-08.pdf |title=Congressional Apportionment (2010 Census Briefs C2010BR-08) |publisher=U.S. Department of Commerce, Economics and Statistics Administration |date=2011-11-01 |access-date=2015-02-25}}</ref> by which seats in the [[United States House of Representatives]] are distributed among the 50 [[U.S. state|states]] according to the most recent decennial [[United States census|census]] mandated by the [[United States Constitution]]. After each state is assigned one seat in the House, most states are then [[Apportionment (politics)|apportioned]] a number of additional seats which roughly corresponds to its share of the aggregate population of the 50 states.<ref>The populations of [[Washington, D.C.]] and [[Territories of the United States|federal territories]] are not included in this figure.</ref> Every state is constitutionally guaranteed two seats in the [[US Senate|Senate]] and at least one seat in the House, regardless of population.

The U.S. House of Representatives' maximum number of seats has been limited to 435, capped at that number by the [[Reapportionment Act of 1929]]—except for a temporary (1959–1962) increase to 437 when [[Alaska]] and [[Hawaii]] were [[Admission to the Union|admitted into the Union]].<ref name="USPL 62-5">[[Public Law 62-5]] of 1911.</ref> The [[Huntington–Hill method|Huntington–Hill method of equal proportions]] has been used to distribute the seats among the states since the [[1940 United States census|1940 census]] reapportionment.<ref name="Kristin D. Burnett"/><ref name="ams"/> Federal law requires the [[clerk of the United States House of Representatives]] to notify each state government of the number of seats apportioned to the state no later than January 25 of the year immediately following each decennial [[United States census|census]].

The size of a state's total congressional delegation (which in addition to representative(s) includes 2 [[U.S. Senate|senators]] for each state) also determines the size of its representation in the [[United States Electoral College|U.S. Electoral College]], which [[United States presidential election|elects the U.S. president]].

==Constitutional context==
{{United States House of Representatives}}
[[Article One of the United States Constitution|Article One]], Section 2, Clause 3 of the [[United States Constitution]] initially provided:

{{quote|Representatives and direct Taxes shall be apportioned among the several States which may be included within this Union, according to their respective Numbers, which shall be determined by adding to the whole Number of free Persons, including those bound to Service for a Term of Years, and excluding Indians not taxed, [[Three-Fifths Compromise|three fifths of all other Persons]].

The Number of Representatives shall not exceed one for every thirty Thousand, but each State shall have at least one Representative;…}}
The phrase "all other persons" refers to slaves, a word not used in the Constitution until the [[Thirteenth Amendment to the United States Constitution|Thirteenth Amendment]].

Following the end of the [[American Civil War|Civil War]], the first of those provisions was superseded by Section 2 of the [[Fourteenth Amendment to the United States Constitution|Fourteenth Amendment]]:

{{quote|Representatives shall be apportioned among the several States according to their respective numbers, counting the whole number of persons in each State, excluding Indians not taxed.<ref>Rendered ''[[Mootness|moot]]'' by the [[Revenue Act of 1924]] and [[Indian Citizenship Act of 1924]].</ref> But when the right to vote at any election for the choice of electors for President and Vice-President of the United States, Representatives in Congress, the Executive and Judicial officers of a State, or the members of the Legislature thereof, is denied to any of the male inhabitants of such State, being twenty-one years of age, and citizens of the United States, or in any way abridged, except for participation in rebellion, or other crime, the basis of representation therein shall be reduced in the proportion which the number of such male citizens shall bear to the whole number of male citizens twenty-one years of age in such State.}}

The phrase "counting the whole number of persons in each State" has traditionally been understood to include non-citizens for purposes of apportionment.<ref>{{Cite web|title=Apportioning Seats in the U.S. House of Representatives Using the 2013 Estimated Citizen Population|url=https://crsreports.congress.gov/product/pdf/R/R41636|access-date=2021-03-26|work = Congressional Research Service}}</ref>

==Reapportionment==
Reapportionments normally occur following each decennial census, though the law that governs the total number of representatives and the method of apportionment to be carried into force at that time are enacted prior to the census.

The decennial apportionment also determines the size of each state's representation in the [[Electoral College (United States)|U.S. Electoral College]]. Under [[Article Two of the United States Constitution|Article II, Section 1, Clause 2]] of the U.S. Constitution, the number of electors of any state equals the size of its total congressional delegation (House and Senate seats).

Federal law requires the [[Clerk of the United States House of Representatives|Clerk of the House of Representatives]] to notify each state government no later than January 25 of the year immediately following the census of the number of seats to which it is entitled. Whether or not the number of seats has changed, the state determines the boundaries of [[List of United States congressional districts|congressional districts]]—geographical areas within the state of approximately equal population—in a process called [[redistricting]].<ref>{{usc|2|2c}}</ref>

Because the deadline for the House Clerk to report the results does not occur until the following January, and the states need sufficient time to perform the redistricting, the decennial census does not affect the elections that are held during that same year. For example, the electoral college apportionment and congressional races during the 2020 presidential election year were still based on the 2010 census results; all of the newly redrawn districts based on the 2020 census did not finally come into force until the 2022 midterm election winners were inaugurated in January 2023.{{Cn|date=July 2024}}

==Number of members==
{{More citations needed section|date=July 2024}}
[[File:US population per representative.svg|thumb|upright=1.35|The U.S. population has increased more rapidly than the membership of the House of Representatives.]]

The size of the U.S. House of Representatives refers to the total number of congressional districts (or seats) into which the land area of the United States proper has been divided. The number of voting representatives is currently [[Reapportionment Act of 1929|set at 435]]. There are an additional five [[Non-voting members of the United States House of Representatives|delegates to the House of Representatives]]. They represent the [[District of Columbia]] and the territories of [[American Samoa]], [[Guam]], the [[Northern Mariana Islands]], which first elected a representative in 2008,<ref>[http://www.saipantribune.com/newsstory.aspx?cat=1&newsID=79834 Bush signs federalization bill] {{Webarchive|url=https://web.archive.org/web/20090213232012/http://www.saipantribune.com/newsstory.aspx?cat=1&newsID=79834 |date=February 13, 2009 }}, Agnes E. Donato, Saipan Tribune, May 10, 2008.</ref> and the [[U.S. Virgin Islands]]. [[Puerto Rico]] also elects a [[Resident Commissioner of Puerto Rico|resident commissioner]] every four years.

===Controversy and history===
Since 1789, when the [[United States Congress]] first convened under the Constitution, the number of citizens per congressional district has risen from an average of 33,000 in 1790 to over 700,000 {{As of|2018|lc=on}}. Prior to the 20th century, the number of representatives increased every decade as more states joined the union, and the population increased.

{| class="wikitable" style="float:right"
|+ Representation in the House, historical

|- style="vertical-align:bottom;"
! Starting<br/>year{{ref|Year|Y}}
! Source
! Avg. constituents<br/>per member

|-
| [[1792 United States House of Representatives elections|1793]]
| nowrap | [[1790 United States census|1790 census]]
| 34,436

|-
| [[1802 United States House of Representatives elections|1803]]
| [[1800 United States census|1800 census]]
| 34,609

|-
| [[1812 United States House of Representatives elections|1813]]
| [[1810 United States census|1810 census]]
| 36,377

|-
| [[1822 United States House of Representatives elections|1823]]
| [[1820 United States census|1820 census]]
| 42,124

|-
| [[1832 United States House of Representatives elections|1833]]
| [[1830 United States census|1830 census]]
| 49,712

|-
| [[1842 United States House of Representatives elections|1843]]
| [[1840 United States census|1840 census]]
| 71,338

|-
| [[1852 United States House of Representatives elections|1853]]
| [[1850 United States census|1850 census]]
| 93,020

|-
| [[1862 United States House of Representatives elections|1863]]
| [[1860 United States census|1860 census]]
| 122,614

|-
| [[1872 United States House of Representatives elections|1873]]
| [[1870 United States census|1870 census]]
| 130,533

|-
| [[1882 United States House of Representatives elections|1883]]
| [[1880 United States census|1880 census]]
| 151,912

|-
| [[1892 United States House of Representatives elections|1893]]
| [[1890 United States census|1890 census]]
| 173,901

|-
| [[1902 United States House of Representatives elections|1903]]
| [[1900 United States census|1900 census]]
| 193,167

|-
| [[1912 United States House of Representatives elections|1913]]
| [[1910 United States census|1910 census]]
| 210,583

|-
| [[1922 United States House of Representatives elections|1923]]
| [[1920 United States census|1920 census]]
| 243,728

|-
| [[1932 United States House of Representatives elections|1933]]
| [[1930 United States census|1930 census]]
| 280,675

|-
| [[1942 United States House of Representatives elections|1943]]
| [[1940 United States census|1940 census]]
| 301,164

|-
| [[1952 United States House of Representatives elections|1953]]
| [[1950 United States census|1950 census]]
| 334,587

|-
| [[1962 United States House of Representatives elections|1963]]
| [[1960 United States census|1960 census]]
| 410,481

|-
| [[1972 United States House of Representatives elections|1973]]
| [[1970 United States census|1970 census]]
| 469,088

|-
| [[1982 United States House of Representatives elections|1983]]
| [[1980 United States census|1980 census]]
| 510,818

|-
| [[1992 United States House of Representatives elections|1993]]
| [[1990 United States census|1990 census]]
| 571,477

|-
| [[2002 United States House of Representatives elections|2003]]
| [[2000 United States census|2000 census]]
| 646,946

|-
| [[2012 United States House of Representatives elections|2013]]
| [[2010 United States census|2010 census]]
| 709,760

|-
| [[2022 United States House of Representatives elections|2023]]
| [[2020 United States census|2020 census]]
| 761,169

|-
| colspan="3" | 
{{note label|Year|Y||Elections are held the preceding year}}<br />
|}

The ideal number of members has been a contentious issue since the country's founding. [[George Washington]] agreed that the original representation proposed during the [[Philadelphia Convention|Constitutional Convention]] (one representative for every 40,000) was inadequate and supported an alteration to reduce that number to 30,000.<ref>{{Cite news |last=Goldberg |first=Jonah |date=January 15, 2001 |title=George Will Called Me An Idiot |language=en-US |work=National Review |url=https://www.nationalreview.com/2001/01/george-will-called-me-idiot-jonah-goldberg/ |url-status=live |access-date=April 11, 2018 |archive-url=https://web.archive.org/web/20090213221035/http://article.nationalreview.com/?q=NTMxYWU4ZjU1M2U5NmJhZjc4YjRiY2Y2NTc4MjNjM2M= |archive-date=February 13, 2009}}</ref> This was the only time that Washington pronounced an opinion on any of the actual issues debated during the entire convention.<ref>[http://avalon.law.yale.edu/18th_century/debates_917.asp Madison's notes on the Constitutional Convention - Tuesday September 17, 1787]</ref> Five years later, Washington was so insistent on having no more than 30,000 constituents per representative that he exercised the first presidential [[veto]] in history on [[Apportionment_Act_of_1792#Review|a bill]] which allowed half states to go over the quota.

In [[Federalist No. 55]], [[James Madison]] argued that the size of the House of Representatives has to balance the ability of the body to legislate with the need for legislators to have a relationship close enough to the people to understand their local circumstances, that such representatives' social class be low enough to sympathize with the feelings of the mass of the people, and that their power be diluted enough to limit their abuse of the public trust and interests.

{{quote|... first, that so small a number of representatives will be an unsafe depositary of the public interests; secondly, that they will not possess a proper knowledge of the local circumstances of their numerous constituents; thirdly, that they will be taken from that class of citizens which will sympathize least with the feelings of the mass of the people, and be most likely to aim at a permanent elevation of the few on the depression of the many; ...<ref name="The Federalist #55">{{Cite web |title=The Federalist #55 |url=http://constitution.org/fed/federa55.htm |access-date=2020-06-23 |website=constitution.org}}</ref><ref name="Federalist 55 citation 2">{{cite web |title=Founders Online: The Federalist No. 55, [13 February 1788] |url=https://founders.archives.gov/documents/Hamilton/01-04-02-0204 |website=founders.archives.gov |access-date=16 May 2024 |language=en}}</ref>}}

Madison also addressed Anti-Federalist claims that the representation would be inadequate, arguing that the major inadequacies are of minimal inconvenience since these will be cured rather quickly by virtue of decennial reapportionment. He noted, however,

{{quote|I take for granted here what I shall, in answering the fourth objection, hereinafter show, that the number of representatives will be augmented from time to time in the manner provided by the Constitution. On a contrary supposition, I should admit the objection to have very great weight indeed.}}

Madison argued against the assumption that more is better:

{{quote|Sixty or seventy men may be more properly trusted with a given degree of power than six or seven. But it does not follow that six or seven hundred would be proportionally a better depositary. And if we carry on the supposition to six or seven thousand, the whole reasoning ought to be reversed. ... In all very numerous assemblies, of whatever character composed, passion never fails to wrest the scepter from reason.<ref name="The Federalist #55" />}}

==== Global comparison and disparities ====
When talking about the populations within California's reapportioned [[California's congressional districts|House districts]] in 1951, a report from [[Duke University]] found that "[there] is not an excessive disparity in district populations, but [the populations and disparities are] perhaps larger than necessary."<ref>{{Cite journal|last=Todd|first=James|url=https://scholarship.law.duke.edu/cgi/viewcontent.cgi?referer=https://www.google.com/&httpsredir=1&article=2528&context=lcp|title=Law and Contemporary Problems: Legislative Apportionment (Chapter Title: The Apportionment Problem Faced by the States)|journal=Law and Contemporary Problems|publisher=[[Duke University]]|year=1952|volume=17|issue=2|location=Durham, North Carolina|pages=314–337|eissn=1945-2322|issn=1945-2322}}</ref> If the House had a similar ratio of representatives to constituents as it did after the [[1930 United States census]], it would currently have 1,156 members (still just the second largest lower house, after [[National People's Congress|China]]).<ref name=":0">{{Cite web|last=DeSilver|first=Drew|date=May 31, 2018|title=U.S. population keeps growing, but House of Representatives is same size as in Taft era|url=https://www.pewresearch.org/fact-tank/2018/05/31/u-s-population-keeps-growing-but-house-of-representatives-is-same-size-as-in-taft-era/|website=[[Pew Research Center]]}}</ref>

The United States has unusually large constituencies compared to other [[OECD]] countries,<ref name=":0" /> the [[List of legislatures by number of members|third largest]] in the world. However, most of this is caused by the United States's large population, which is the third-largest in the world; legislatures typically grow [[Cube root law|in proportion to the cube root of the population]], rather than linearly, meaning larger countries tend to have larger constituency sizes.{{cn|reason=In this sentence, there are no citations to substantiate the claim(s) made from "legislatures" onward.|date=August 2024}}

=== Membership cap===
The [[Apportionment Act of 1911]] ([[Public Law 62-5]]) raised the membership of the U.S. House to 433 and provided for an apportionment. It also provided for additional seats upon the admissions of [[Arizona]] and [[New Mexico]] as states, increasing the number to 435 in 1912.

In 1921, Congress failed to reapportion the House membership as required by the United States Constitution. This failure to reapportion may have been politically motivated, as the [[United States House of Representatives elections, 1920|newly elected Republican majority]] may have feared the effect such a reapportionment would have on their future electoral prospects.<ref>{{cite book |title=Fair Representation, Meeting The Ideal of One Man One vote" |author1-link=Michel Balinski |author1-first=Michel |author1-last=Balinski |author2-first=H. Peyton |author2-last=Young |page=51}}</ref><ref>{{Cite web |title= Congressional Apportionment |work=NationalAtlas.gov |url=http://www.nationalatlas.gov/articles/boundaries/a_conApport.html#seven |url-status=dead |archive-url=https://web.archive.org/web/20090228091000/http://www.nationalatlas.gov/articles/boundaries/a_conApport.html#seven |archive-date=February 28, 2009 |access-date=February 15, 2009}}</ref> A reapportionment in 1921 in the traditional fashion would have increased the size of the House to 483 seats,{{cn|date=January 2021}} but many members would have lost their seats due to the population shifts, and the House chamber did not have adequate seats for 483 members. By 1929, no reapportionment had been made since 1911, and there was vast representational inequity, measured by the average district size. By 1929 some states had districts twice as large as others due to population growth and demographic shift.<ref>{{Cite journal |title=Apportionment of Representatives in Congress |url=http://library.cqpress.com/cqresearcher/document.php?id=cqresrre1927120600 |journal=CQ Researcher by CQ Press | series=CQ Researcher Online | year=1927 | page=975 |language=en |issn=1942-5635}}</ref>

In 1929 Congress (with Republican control of both houses of Congress and the presidency) passed the [[Reapportionment Act of 1929]] which capped the size of the House at 435 and established a permanent method for apportioning a constant 435 seats. This cap has remained unchanged since then, except for a temporary increase to 437 members (twice, in [[86th United States Congress|1959]] and [[87th United States Congress|1961]]) upon the 1959 admission of [[Alaska]] and [[Hawaii]] into the Union.<ref name="USHouseO&D">{{Cite web |title=Proportional Representation |url=http://history.house.gov/Institution/Origins-Development/Proportional-Representation/ |access-date=September 21, 2018 |publisher=Office of the Historian, United States House of Representatives |location=Washington, D.C.}}</ref>

Two states, [[Wyoming]] and [[Vermont]], have populations smaller than the average for a single district, although neither state has fewer people than the least populous congressional districts.

===Proposed expansion===
Among the [[Bill of Rights (United States)|Bill of Rights]] amendments to the United States Constitution proposed by Congress in 1789, was one [[Congressional Apportionment Amendment|addressing the number of seats in the House]]. It attempted to set a pattern for growth of the House along with the population, but has not been ratified.

{{blockquote|After the first [[United States census|enumeration]] required by the first article of the Constitution, there shall be one Representative for every thirty thousand, until the number shall amount to one hundred, after which the proportion shall be so regulated by Congress, that there shall be not less than one hundred Representatives, nor less than one Representative for every forty thousand persons, until the number of Representatives shall amount to two hundred; after which the proportion shall be so regulated by Congress, that there shall not be less than two hundred Representatives, nor more than one Representative for every fifty thousand persons.<ref name="AmendmentsNotRatified">{{Cite web |title=Constitutional Amendments Not Ratified |url=http://www.house.gov/house/Amendnotrat.shtml |url-status=live |archive-url=https://web.archive.org/web/20070927073820/http://www.house.gov/house/Amendnotrat.shtml |archive-date=27 September 2007 |access-date=2007-09-30 |publisher=United States House of Representatives}}</ref>}}

Taken at face-value, with the nation's population reaching approximately 308.7 million according to the [[2010 United States census|2010 census]], the proposed amendment would have called for an up-to 6,000-member House.<ref>{{Cite web |url=https://mereorthodoxy.com/congressional-apportionment-amendment/ |title=Pack the House: How to Fix the Legislative Branch |last=Stone |first=Lyman |date=October 17, 2018 |publisher=Mere Orthodoxy |access-date=September 17, 2019}}</ref><ref>{{Cite web |url=https://www.vox.com/2018/6/4/17417452/congress-representation-ratio-district-size-chart-graph |title=The case for massively expanding the US House of Representatives, in one chart |last=Matthews |first=Dylan |author-link=Dylan Matthews |date=June 4, 2018 |publisher=Vox |access-date=September 17, 2019}}</ref><ref>{{Cite web |url=https://www.conservativenewsandviews.com/2015/04/16/constitution/packing-the-house/ |title=Packing the House? |last=Hurlbut |first=Terry |date=April 16, 2015 |publisher=Conservative News and Views |access-date=September 17, 2019}}</ref> However, in the context of its original construction, the amendment may have instead outlined an iterative procedure for apportionment following a [[square root rule]] relative to the population (e.g. <math display="inline">Representatives \approx \sqrt{10000+Population/100} - 100</math>) that would still have called for a more than 1,600-member House following the same 2010 census.<ref>{{Cite book |last=Kyvig |first=David |title=Explicit and Authentic Acts |publisher=University Press of Kansas |year=2016 |isbn=978-0-7006-2229-0 |pages=470}}</ref><ref>{{Cite web |title=Madison Apportionment Amendment |url=https://genuineideas.com/ArticlesIndex/districtsize.html |access-date=2023-09-07 |website=genuineideas.com}}</ref> 

One proposal to alleviate the current constituency disparities and the high average number of constituents in many states' congressional districts is the "[[Wyoming Rule|Wyoming rule]]." Operating similar to New Zealand's [[New Zealand electorates#Distribution|method of allocation]] for proportional representation, it would give the least populous state (which has been [[List of U.S. states and territories by historical population|Wyoming since 1990]]) one representative and then create districts in other states with the same population.<ref>{{Cite web|last=Taylor|first=Steven|date=December 14, 2010|title=Representation in the House: The Wyoming Rule|url=https://www.outsidethebeltway.com/representation-in-the-house-the-wyoming-rule/|website=Outside the Beltway}}</ref>

Another proposed expansion rule, the [[cube root rule]],<ref>{{Cite book|last1=Kane|first1=Caroline|url=https://www.fordham.edu/download/downloads/id/14402/Why_the_House_Must_Be_Expanded___Democracy_Clinic.pdf|title=Why the House of Representatives Must Be Expanded and How Today's Congress Can Make it Happen|last2=Mascioli|first2=Gianni|last3=McGarry|first3=Michael|last4=Nagel|first4=Meira|publisher=Fordham University School of Law|year=2020|isbn=|location=|pages=}}</ref> calls for the membership of the legislature to be based on the [[cube root]] (rounded up) of the U.S. population at the last census. For example, such a rule would call for 692 members of the House based on the 2020 United States census. An additional House member would be added each time the ''national'' population ''exceeds'' the next cube; in this case, the next House member would be added when the census population reached 331,373,889, and the one after that at 332,812,558. A variation would split the representation between the House and the Senate, e.g. 592 members in the House (692 − 100 senators).<ref>{{Cite web|title=The "Cube Root Rule": A Push to Make Congress More Representative?|url=https://ivn.us/2017/10/16/cube-root-rule-push-make-congress-representative/|access-date=May 31, 2019|website=IVN|date=October 16, 2017|publisher=Independent Voter Network}}</ref> 

On May 21, 2001, Rep. [[Alcee Hastings]] sent a [[Dear colleague letter (United States)|dear colleague letter]] pointing out that U.S. expansion of its legislature had not kept pace with other countries.<ref>{{Cite web |date=June 2, 2006 |title=FairVote - Hastings Letter |url=http://www.fairvote.org/?page=866 |archive-url=https://web.archive.org/web/20060602021508/http://www.fairvote.org/?page=866 |url-status=dead |archive-date=June 2, 2006 |access-date=June 23, 2020 }}</ref>

In 2007, during the {{USCongressOrdinalCongress|110}}, [[Thomas M. Davis|Representative Tom Davis]] introduced a bill in the House of Representatives that would add two seats to the House, one for Utah and one for the [[District of Columbia]]. It was passed by the House, but was tripped up by procedural hurdles in the Senate and withdrawn from consideration. An identical bill was reintroduced during the {{USCongressOrdinalCongress|110}}. In February 2009 the Senate adopted the measure 61–37. In April 2010, however, House leaders decided to shelve the proposal.<ref>{{Cite news |last1=Marimow |first1=Ann E. |last2=Pershing |first2=Ben |date=April 21, 2010 |title=Congressional leaders shelve D.C. voting rights bill |newspaper=The Washington Post |url=https://www.washingtonpost.com/wp-dyn/content/article/2010/04/20/AR2010042004796.html}}</ref>

Two provisions of Section 102, subsection (d) in the [[Washington, D.C., Admission Act]] by delegate [[Eleanor Holmes Norton]] and its same-titled Senate companion by Sen. [[Tom Carper]], both introduced in 2021 and again in 2023 during the {{USCongressOrdinal|117}} and {{USCongressOrdinalCongress|118}}es, seek to amend Section 22(a) of the Reapportionment Act by adding one to the permanent House membership for a total of 436 representatives as the state of Washington, Douglass Commonwealth (i.e., Washington, D.C.) would have been entitled to an at-large district.<ref>{{USBill|118|HR|51}}</ref><ref>{{USBill|118|S|51}}</ref> Holmes Norton's bill previously passed the House during the {{USCongressOrdinalCongress|116}} but not the Senate.<ref>{{Cite web|url=https://www.vox.com/2020/6/22/21293168/dc-statehood-vote-filibuster-supreme-court-joe-biden|title=DC is closer to becoming a state now than it has ever been|last=Millhiser|first=Ian|date=June 26, 2020|work=Vox}}</ref>

==Apportionment methods==
{| class="wikitable sortable mw-collapsible mw-collapsed" style="float:right"
|+ Apportionment in the House of the US population, 2010–2019
! rowspan="2" |State
! colspan="2" |Population percent 
! colspan="2" |House percent
|- style="vertical-align:bottom;"
!2019
!2010
!2019<ref group="note">2019 numbers are calculations from estimated population data</ref>
!2010
|-
| {{Flag|California}}
|12.06%
|12.09%
|11.95%
|12.18%
|-
|{{Flag|Texas}}
|8.85%
|8.16%
|8.74%
|8.28%
|-
|{{Flag|Florida}}
|6.56%
|6.10%
|6.44%
|6.21%
|-
|{{Flag|New York}}
|5.94%
|6.29%
|5.98%
|6.21%
|-
|{{Flag|Pennsylvania}}
|3.91%
|4.12%
|3.91%
|4.14%
|-
|{{Flag|Illinois}}
|3.87%
|4.16%
|3.91%
|4.14%
|-
|{{Flag|Ohio}}
|3.57%
|3.74%
|3.68%
|3.68%
|-
|{{Flag|Georgia (U.S. state)|name=Georgia}}
|3.24%
|3.14%
|3.22%
|3.22%
|-
|{{Flag|North Carolina}}
|3.20%
|3.09%
|3.22%
|2.99%
|-
|{{Flag|Michigan}}
|3.05%
|3.21%
|2.99%
|3.22%
|-
|{{Flag|New Jersey}}
|2.71%
|2.85%
|2.76%
|2.76%
|-
|{{Flag|Virginia}}
|2.61%
|2.60%
|2.53%
|2.53%
|-
|{{Flag|Washington}}
|2.32%
|2.18%
|2.30%
|2.30%
|-
|{{Flag|Arizona}}
|2.22%
|2.07%
|2.30%
|2.07%
|-
|{{Flag|Massachusetts}}
|2.10%
|2.12%
|2.07%
|2.07%
|-
|{{Flag|Tennessee}}
|2.09%
|2.06%
|2.07%
|2.07%
|-
|{{Flag|Indiana}}
|2.06%
|2.10%
|2.07%
|2.07%
|-
|{{Flag|Missouri}}
|1.87%
|1.94%
|1.84%
|1.84%
|-
|{{Flag|Maryland}}
|1.85%
|1.87%
|1.84%
|1.84%
|-
|{{Flag|Wisconsin}}
|1.78%
|1.85%
|1.84%
|1.84%
|-
|{{Flag|Colorado}}
|1.76%
|1.63%
|1.84%
|1.61%
|-
|{{Flag|Minnesota}}
|1.72%
|1.72%
|1.61%
|1.84%
|-
|{{Flag|South Carolina}}
|1.57%
|1.50%
|1.61%
|1.61%
|-
|{{Flag|Alabama}}
|1.50%
|1.55%
|1.61%
|1.61%
|-
|{{Flag|Louisiana}}
|1.42%
|1.47%
|1.38%
|1.38%
|-
|{{Flag|Kentucky}}
|1.36%
|1.41%
|1.38%
|1.38%
|-
|{{Flag|Oregon}}
|1.29%
|1.24%
|1.38%
|1.15%
|-
|{{Flag|Oklahoma}}
|1.21%
|1.22%
|1.15%
|1.15%
|-
|{{Flag|Connecticut}}
|1.09%
|1.16%
|1.15%
|1.15%
|-
|{{Flag|Utah}}
|0.98%
|0.90%
|0.92%
|0.92%
|-
|{{Flag|Iowa}}
|0.96%
|0.99%
|0.92%
|0.92%
|-
|{{Flag|Nevada}}
|0.94%
|0.88%
|0.92%
|0.92%
|-
|{{Flag|Arkansas}}
|0.92%
|0.95%
|0.92%
|0.92%
|-
|{{Flag|Mississippi}}
|0.91%
|0.96%
|0.92%
|0.92%
|-
|{{Flag|Kansas}}
|0.89%
|0.93%
|0.92%
|0.92%
|-
|{{Flag|New Mexico}}
|0.64%
|0.67%
|0.69%
|0.69%
|-
|{{Flag|Nebraska}}
|0.59%
|0.59%
|0.69%
|0.69%
|-
|{{Flag|West Virginia}}
|0.55%
|0.60%
|0.46%
|0.69%
|-
|{{Flag|Idaho}}
|0.55%
|0.51%
|0.46%
|0.46%
|-
|{{Flag|Hawaii}}
|0.43%
|0.44%
|0.46%
|0.46%
|-
|{{Flag|New Hampshire}}
|0.42%
|0.43%
|0.46%
|0.46%
|-
|{{Flag|Maine}}
|0.41%
|0.43%
|0.46%
|0.46%
|-
|{{Flag|Montana}}
|0.33%
|0.32%
|0.46%
|0.23%
|-
|{{Flag|Rhode Island}}
|0.32%
|0.34%
|0.23%
|0.46%
|-
|{{Flag|Delaware}}
|0.30%
|0.29%
|0.23%
|0.23%
|-
|{{Flag|South Dakota}}
|0.27%
|0.26%
|0.23%
|0.23%
|-
|{{Flag|North Dakota}}
|0.23%
|0.22%
|0.23%
|0.23%
|-
|{{Flag|Alaska}}
|0.22%
|0.23%
|0.23%
|0.23%
|-
|{{Flag|Vermont}}
|0.19%
|0.20%
|0.23%
|0.23%
|-
|{{Flag|Wyoming}}
|0.18%
|0.18%
|0.23%
|0.23%
|-
| colspan="5" |<references group="note" />
|}
Apart from the requirement that each state is to be entitled to at least one representative in the House of Representatives, the number of representatives in each state is in principle to be proportional to its population. Since the adoption of the [[United States Constitution|Constitution]], five distinct apportionment methods have been used.

[[File:USCongressionalRedistrictingPartisanControl2020.svg|upright=1.0|thumb|Partisan control of congressional redistricting after the 2020 elections, with the number of U.S. House seats each state will receive.
{{legend|#2c82b6|Democratic control}}
{{legend|#d63f3f|Republican control}}
{{legend|#ecc61c|Split or bipartisan control}}
{{legend|#60c53a|Independent redistricting commission}}
{{legend|#c0c0c0|No redistricting necessary}}]]
The first apportionment was contained in [[Article One of the United States Constitution#Clause 3: Apportionment of Representatives and taxes|Art. I, § 2, cl. 3 of the Constitution]]. After the first census in 1790, Congress passed the [[Apportionment Act of 1792]] and adopted the [[D'Hondt method#Jefferson and D'Hondt|Jefferson method]] to apportion U.S. representatives to the states based on population.<ref>3 Annals of Cong. 539 (1792)</ref> The Jefferson method required fractional [[remainder]]s to be discarded when calculating each state's total number of U.S. representatives and was used until the 1830 census.<ref>Act of Jan. 14, 1802, {{USStat|2|128}}</ref><ref>Act of Dec. 21, 1811, {{USStat|2|669}}</ref><ref>Act of Mar. 7, 1822, {{USStat|3|651}}</ref><ref>Act of May 22, 1832, {{USStat|4|516}}</ref> The [[Sainte-Laguë method|Webster method]],  proposed in 1832 by [[Daniel Webster]] and adopted for the 1840 census, allocated an additional representative to states with a fractional remainder greater than 0.5.<ref>Act of 25 June 1842, ch 46, {{USStat|5|491}}</ref> 

From 1850 to 1900, the situation was substantially less clear. Congress passed a law in 1850 declaring future apportionment would be done with [[Hamilton's method]]. However, Congress continued to pass ad hoc apportionment bills from 1850 through 1900, in each case overruling the procedure laid out in the 1850 census. This was particularly true after the 1860 Census: the national situation was complicated by the [[American Civil War|Civil War]]), and no real apportionment method was used. Apart from 1860, Congress deliberately chose after each census to set the size of the House at a level where Hamilton and Webster's methods gave the same apportionment.<ref>{{Cite book|last1=Balinski |first1=Michael L. |last2=Young |first2=H. Peyton |year=1982 |title=Fair Representation: Meeting the Ideal of One Man, One Vote |place=New Haven, CT |publisher=Yale University Press |url=https://books.google.com/books?id=eBFNzSeAv_sC |isbn=0-8157-0090-3}}</ref> This unofficial adoption of [[Webster's method]]  was driven by the discovery of the [[Alabama paradox]], which created an uproar in the House.<ref name="HistoricalApportionment">{{cite web|title=Congressional Apportionment-Historical Perspective |url=https://www.census.gov/population/apportionment/about/history.html |publisher=U.S. Census Bureau|access-date=27 October 2013}}.</ref> The [[Apportionment Act of 1911]], in addition to setting the number of U.S. representatives at 435, returned to the Webster method, which was used following the 1910 and 1930 censuses (no reapportionment was done after the 1920 census). The current method, known as the [[Huntington–Hill method]] or method of equal proportions, was adopted in 1941 for reapportionment based on the 1940 census and beyond.<ref name="Kristin D. Burnett" /><ref name="ams">{{Cite web|title=The History of Apportionment in America |publisher=American Mathematical Society |url=http://www.ams.org/featurecolumn/archive/apportion2.html |access-date=2009-02-15}}</ref><ref>{{Cite web|title=2 USC §2a |publisher=Cornell University Law School, Legal Information Institute |url=https://www.law.cornell.edu/uscode/text/02/2a- |access-date=2008-05-13}}</ref><ref>{{Cite web|title=Computing Apportionment |publisher=U.S. Census Bureau |url=https://www.census.gov/population/www/censusdata/apportionment/computing.html |access-date=2009-02-14}}</ref> The revised method was necessary in the context of the cap on the number of representatives set in the [[Reapportionment Act of 1929]].{{Cn|date=July 2024}}

===Method of equal proportions===
{{Further|Huntington–Hill method}} 
The apportionment method currently used is the method of equal proportions, which minimizes the [[percentage difference]]s in the number of people per representative among the different states.<ref>{{Cite web |title=Congressional Apportionment |website=NationalAtlas.gov |publisher=U.S. Department of the Interior |url=http://www.nationalatlas.gov/articles/boundaries/a_conApport.html#six |archive-url=https://web.archive.org/web/20081030080614/http://www.nationalatlas.gov/articles/boundaries/a_conApport.html#six |archive-date=2008-10-30 |access-date=2009-02-14 |url-status=dead }}</ref> The resulting apportionment is optimal in the sense that any additional transfer of a seat from one state to another would result in larger percentage differences.<ref>{{cite journal|author=Edward V Huntington |title=The Mathematical Theory of the Apportionment of Representatives |journal=Proceedings of the National Academy of Sciences of the United States of America |year=1921 |pmc=1084767 |pmid=16576591 |volume=7 |issue=4 |pages=123–7 |doi=10.1073/pnas.7.4.123|bibcode=1921PNAS....7..123H |doi-access=free }}</ref>

In this method, as a first step, each of the 50 states is given its one guaranteed seat in the House of Representatives, leaving 385 seats to assign. The remaining seats are allocated one at a time, to the state with the highest priority number. Thus, the 51st seat would go to the most populous state (currently California). The priority number is determined by the ratio of the state population to the [[geometric mean]] of the number of seats it currently holds in the assignment process, ''n'' (initially 1), and the number of seats it ''would'' hold ''if'' the seat were assigned to it, ''n''+1. Symbolically, the priority number ''A<sub>n</sub>'' is

:<math> A_{n} = \frac{P}{\sqrt{n(n+1)}} </math>

where ''P'' is the population of the state, and ''n'' is the number of seats it currently holds before the possible allocation of the next seat.  An equivalent, recursive definition is

:<math> A_{m+1} = \sqrt{\frac{m}{m+2}} \ A_{m} </math>
:<math> A_{n} = \sqrt{\frac{n-1}{n+1}} \ A_{n-1} </math>

where ''n'' is '''still''' the number of seats the state has '''before''' allocation of the next (in other words, for the ''m''th allocation, ''n'' = ''m''-1).

Consider the reapportionment following the 2010 U.S. census: beginning with all states initially being allocated one seat, the largest value of ''A''<sub>1</sub> corresponds to the largest state, California, which is allocated seat 51. After being allocated its 2nd seat, its priority value decreases to its ''A''<sub>2</sub> value, which is reordered to a position back in line. The 52nd seat goes to Texas, the 2nd largest state, because its ''A''<sub>1</sub> priority value is larger than the ''A<sub>n</sub>'' of any other state. However, the 53rd seat goes back to California because its ''A''<sub>2</sub> priority value is larger than the ''A<sub>n</sub>'' of any other state. The 54th seat goes to New York because its ''A''<sub>1</sub> priority value is larger than the ''A<sub>n</sub>'' of any other state at this point. This process continues until all remaining seats are assigned. Each time a state is assigned a seat, ''n'' is incremented by 1, causing its priority value to be reduced and reordered among the states, whereupon another state normally rises to the top of the list.

The 2010 census ranking of priority values<ref>{{Cite web|title=Priority Values for 2010 Census |publisher=U.S. Bureau of the Census |url=https://www2.census.gov/programs-surveys/decennial/2010/data/apportionment/PriorityValues2010.pdf |access-date=2020-08-29}}</ref> shows the order in which seats 51–435 were apportioned after the 2010 census, with additional listings for the next five priorities. [[Minnesota]] was allocated the final (435th) seat. [[North Carolina]] missed its 14th seat by 15,754 residents as the 436th seat to be allocated; ten years earlier it had gained its 13th seat as the 435th seat to be allocated based on the 2000 census.<ref>{{Cite web|title=Census 2000 Ranking of Priority Values |publisher=U.S. Bureau of the Census |date=2001-02-21 |url=https://www.census.gov/population/censusdata/apportionment/00pvalues.txt |access-date=2008-05-13}}</ref>

The 2020 census ranking of priority values<ref>{{Cite web|title=Priority Values for 2020 Census|url=https://www2.census.gov/programs-surveys/decennial/2020/data/apportionment/2020PriorityValues.pdf|access-date=2021-04-27|publisher=U.S. Bureau of the Census}}</ref> shows the order in which seats 51–435 were apportioned after the 2020 census, with additional listings for the next ten priorities. For the second time in a row, Minnesota was allocated the final (435th) seat. If either New York had registered 89 more residents or Minnesota had registered 26 fewer residents, New York would have been allocated the 435th seat instead.<ref>{{Cite news|last=Goldmacher|first=Shane|date=2021-04-26|title=New York Loses House Seat After Coming Up 89 People Short on Census|language=en-US|work=The New York Times|url=https://www.nytimes.com/2021/04/26/nyregion/new-york-census-congress.html|access-date=2021-04-28|issn=0362-4331}}</ref><ref>{{Cite news|last=Wang|first=Hansi Lo|date=2021-05-01|title=How 26 People In The Census Count Helped Minnesota Beat New York For A House Seat|url=https://www.npr.org/2021/05/01/991671730/how-26-people-in-the-census-count-helped-minnesota-beat-new-york-for-a-house-sea|access-date=2021-05-17}}</ref>

==Past apportionments==
''Note: The first apportionment was established by the Constitution based on population estimates made by the [[Philadelphia Convention]], and was not based on any census or enumeration.''

{{backgroundcolor|lightgray|'''Bold'''}} indicates the largest number of representatives each state has had.
{| class="wikitable nowraplinks sortable" style="text-align:center; font-size:85%; line-height:1.2; vertical-align:bottom"

|-
! rowspan="5" | State{{shy}}hood<br>order
! Census
! style="padding:0;" | [[Article One of the United States Constitution#Clause 3: Apportionment of Representatives and taxes|Const.]]
! [[1790 United States census|1st]]
! [[1800 United States census|2nd]]
! [[1810 United States census|3rd]]
! [[1820 United States census|4th]]
! [[1830 United States census|5th]]
! [[1840 United States census|6th]]
! [[1850 United States census|7th]]
! [[1860 United States census|8th]]
! [[1870 United States census|9th]]
! [[1880 United States census|10th]]
! [[1890 United States census|11th]]
! [[1900 United States census|12th]]
! [[1910 United States census|13th]]
! style="padding:0;" | [[1930 United States census|15th]]{{Efn|Congress failed to pass any reapportionment to implement the [[1920 United States census]] so despite population shift, distribution of seats from 1913 remained in effect until 1933.}}
! [[1940 United States census|16th]]
! [[1950 United States census|17th]]
! [[1960 United States census|18th]]
! [[1970 United States census|19th]]
! [[1980 United States census|20th]]
! [[1990 United States census|21st]]
! [[2000 United States census|22nd]]
! [[2010 United States census|23rd]]
! [[2020 United States census|24th]]

|-
! Year
! style="padding:0;" | 1789
! style="padding:0;" | 1790
! style="padding:0;" | 1800
! style="padding:0;" | 1810
! style="padding:0;" | 1820
! style="padding:0;" | 1830
! style="padding:0;" | 1840
! style="padding:0;" | 1850
! style="padding:0;" | 1860
! style="padding:0;" | 1870
! style="padding:0;" | 1880
! style="padding:0;" | 1890
! style="padding:0;" | 1900
! style="padding:0;" | 1910
! style="padding:0;" | 1930
! style="padding:0;" | 1940
! style="padding:0;" | 1950
! style="padding:0;" | 1960
! style="padding:0;" | 1970
! style="padding:0;" | 1980
! style="padding:0;" | 1990
! style="padding:0;" | 2000
! style="padding:0;" | 2010
! style="padding:0;" | 2020

|-
! Effected
! style="padding:0;" | 1789
! style="padding:0;" | 1793
! style="padding:0;" | 1803
! style="padding:0;" | 1813
! style="padding:0;" | 1823
! style="padding:0;" | 1833
! style="padding:0;" | 1843
! style="padding:0;" | 1853
! style="padding:0;" | 1863
! style="padding:0;" | 1873
! style="padding:0;" | 1883
! style="padding:0;" | 1893
! style="padding:0;" | 1903
! style="padding:0;" | 1913
! style="padding:0;" | 1933
! style="padding:0;" | 1943
! style="padding:0;" | 1953
! style="padding:0;" | 1963
! style="padding:0;" | 1973
! style="padding:0;" | 1983
! style="padding:0;" | 1993
! style="padding:0;" | 2003
! style="padding:0;" | 2013
! style="padding:0;" | 2023

|-
! Size
! 65
! 105
! 142
! 182
! 213
! 240
! 223
! 234
! 241
! 292
! 325
! 356
! 386
! colspan="11" | 435

|-
!  | State
! data-sort-type="number" | 
! data-sort-type="number" | 
! data-sort-type="number" | 
! data-sort-type="number" | 
! data-sort-type="number" | 
! data-sort-type="number" | 
! data-sort-type="number" | 
! data-sort-type="number" | 
! data-sort-type="number" | 
! data-sort-type="number" | 
! data-sort-type="number" | 
! data-sort-type="number" | 
! data-sort-type="number" | 
! data-sort-type="number" | 
! data-sort-type="number" | 
! data-sort-type="number" | 
! data-sort-type="number" | 
! data-sort-type="number" | 
! data-sort-type="number" | 
! data-sort-type="number" | 
! data-sort-type="number" | 
! data-sort-type="number" | 
! data-sort-type="number" | 
! data-sort-type="number" | 

|-
! 22
! [[Alabama|AL]]
| –
| –
| –
| –
| 3
| 5
| 7
| 7
| 6
| 8
| 8
| 9
| 9
| {{background color|lightgray|'''10'''}}
| 9
| 9
| 9
| 8
| 7
| 7
| 7
| 7
| 7
| 7

|-
! 49
! [[Alaska|AK]]
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| {{background color|lightgray|'''1'''}}
| {{background color|lightgray|'''1'''}}
| {{background color|lightgray|'''1'''}}
| {{background color|lightgray|'''1'''}}
| {{background color|lightgray|'''1'''}}
| {{background color|lightgray|'''1'''}}
| {{background color|lightgray|'''1'''}}

|-
! 48
! [[Arizona|AZ]]
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| 1
| 1
| 2
| 2
| 3
| 4
| 5
| 6
| 8
| {{backgroundcolor|lightgray|'''9'''}}
|{{backgroundcolor|lightgray|'''9'''}}

|-
! 25
! [[Arkansas|AR]]
| –
| –
| –
| –
| –
| –
| 1
| 2
| 3
| 4
| 5
| 6
| {{background color|lightgray|'''7'''}}
| {{background color|lightgray|'''7'''}}
| {{background color|lightgray|'''7'''}}
| {{background color|lightgray|'''7'''}}
| 6
| 4
| 4
| 4
| 4
| 4
| 4
|4
|-
! 31
! [[California|CA]]
| –
| –
| –
| –
| –
| –
| –
| 2
| 3
| 4
| 6
| 7
| 8
| 11
| 20
| 23
| 30
| 38
| 43
| 45
| 52
| {{background color|lightgray|'''53'''}}
| {{background color|lightgray|'''53'''}}
| 52

|-
! 38
! [[Colorado|CO]]
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| 1
| 2
| 3
| 4
| 4
| 4
| 4
| 4
| 5
| 6
| 6
| 7
| 7
| {{background color|lightgray|'''8'''}}

|-
! 5
! [[Connecticut|CT]]
| 5
| {{background color|lightgray|'''7'''}}
| {{background color|lightgray|'''7'''}}
| {{background color|lightgray|'''7'''}}
| 6
| 6
| 4
| 4
| 4
| 4
| 4
| 4
| 5
| 5
| 6
| 6
| 6
| 6
| 6
| 6
| 6
| 5
| 5
|5
|-
! 1
! [[Delaware|DE]]
| 1
| 1
| 1
| {{background color|lightgray|'''2'''}}
| 1
| 1
| 1
| 1
| 1
| 1
| 1
| 1
| 1
| 1
| 1
| 1
| 1
| 1
| 1
| 1
| 1
| 1
| 1
| 1

|-
! 27
! [[Florida|FL]]
| –
| –
| –
| –
| –
| –
| –
| 1
| 1
| 2
| 2
| 2
| 3
| 4
| 5
| 6
| 8
| 12
| 15
| 19
| 23
| 25
| 27
| {{background color|lightgray|'''28'''}}

|-
! 4
! [[Georgia (U.S. state)|GA]]
| 3
| 2
| 4
| 6
| 7
| 9
| 8
| 8
| 7
| 9
| 10
| 11
| 11
| 12
| 10
| 10
| 10
| 10
| 10
| 10
| 11
| 13
| {{background color|lightgray|'''14'''}}
|{{background color|lightgray|'''14'''}}

|-
! 50
! [[Hawaii|HI]]
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| {{background color|lightgray|'''2'''}}
| {{background color|lightgray|'''2'''}}
| {{background color|lightgray|'''2'''}}
| {{background color|lightgray|'''2'''}}
| {{background color|lightgray|'''2'''}}
| {{background color|lightgray|'''2'''}}
|{{background color|lightgray|'''2'''}}

|-
! 43
! [[Idaho|ID]]
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| 1
| 1
| {{background color|lightgray|'''2'''}}
| {{background color|lightgray|'''2'''}}
| {{background color|lightgray|'''2'''}}
| {{background color|lightgray|'''2'''}}
| {{background color|lightgray|'''2'''}}
| {{background color|lightgray|'''2'''}}
| {{background color|lightgray|'''2'''}}
| {{background color|lightgray|'''2'''}}
| {{background color|lightgray|'''2'''}}
| {{background color|lightgray|'''2'''}}
|{{background color|lightgray|'''2'''}}
|-
! 21
! [[Illinois|IL]]
| –
| –
| –
| –
| 1
| 3
| 7
| 9
| 14
| 19
| 20
| 22
| 25
| {{background color|lightgray|'''27'''}}
| {{background color|lightgray|'''27'''}}
| 26
| 25
| 24
| 24
| 22
| 20
| 19
| 18
| 17

|-
! 19
! [[Indiana|IN]]
| –
| –
| –
| –
| 3
| 7
| 10
| 11
| 11
| {{background color|lightgray|'''13'''}}
| {{background color|lightgray|'''13'''}}
| {{background color|lightgray|'''13'''}}
| {{background color|lightgray|'''13'''}}
| {{background color|lightgray|'''13'''}}
| 12
| 11
| 11
| 11
| 11
| 10
| 10
| 9
| 9
|9
|-
! 29
! [[Iowa|IA]]
| –
| –
| –
| –
| –
| –
| –
| 2
| 6
| 9
| {{background color|lightgray|'''11'''}}
| {{background color|lightgray|'''11'''}}
| {{background color|lightgray|'''11'''}}
| {{background color|lightgray|'''11'''}}
| 9
| 8
| 8
| 7
| 6
| 6
| 5
| 5
| 4
|4
|-
! 34
! [[Kansas|KS]]
| –
| –
| –
| –
| –
| –
| –
| –
| 1
| 3
| 7
| {{background color|lightgray|'''8'''}}
| {{background color|lightgray|'''8'''}}
| {{background color|lightgray|'''8'''}}
| 7
| 6
| 6
| 5
| 5
| 5
| 4
| 4
| 4
|4
|-
! 15
! [[Kentucky|KY]]
| –
| 2
| 6
| 10
| 12
| {{background color|lightgray|'''13'''}}
| 10
| 10
| 9
| 10
| 11
| 11
| 11
| 11
| 9
| 9
| 8
| 7
| 7
| 7
| 6
| 6
| 6
|6
|-
! 18
! [[Louisiana|LA]]
| –
| –
| –
| 1
| 3
| 3
| 4
| 4
| 5
| 6
| 6
| 6
| 7
| {{background color|lightgray|'''8'''}}
| {{background color|lightgray|'''8'''}}
| {{background color|lightgray|'''8'''}}
| {{background color|lightgray|'''8'''}}
| {{background color|lightgray|'''8'''}}
| {{background color|lightgray|'''8'''}}
| {{background color|lightgray|'''8'''}}
| 7
| 7
| 6
|6
|-
! 23
! [[Maine|ME]]
| –
| –
| –
| –
| 7
| {{background color|lightgray|'''8'''}}
| 7
| 6
| 5
| 5
| 4
| 4
| 4
| 4
| 3
| 3
| 3
| 2
| 2
| 2
| 2
| 2
| 2
|2
|-
! 7
! [[Maryland|MD]]
| 6
| 8
| {{background color|lightgray|'''9'''}}
| {{background color|lightgray|'''9'''}}
| {{background color|lightgray|'''9'''}}
| 8
| 6
| 6
| 5
| 6
| 6
| 6
| 6
| 6
| 6
| 6
| 7
| 8
| 8
| 8
| 8
| 8
| 8
|8
|-
! 6
! [[Massachusetts|MA]]
| 8
| 14
| 17
| {{background color|lightgray|'''20'''}}
| 13
| 12
| 10
| 11
| 10
| 11
| 12
| 13
| 14
| 16
| 15
| 14
| 14
| 12
| 12
| 11
| 10
| 10
| 9
|9
|-
! 26
! [[Michigan|MI]]
| –
| –
| –
| –
| –
| –
| 3
| 4
| 6
| 9
| 11
| 12
| 12
| 13
| 17
| 17
| 18
| {{background color|lightgray|'''19'''}}
| {{background color|lightgray|'''19'''}}
| 18
| 16
| 15
| 14
| 13

|-
! 32
! [[Minnesota|MN]]
| –
| –
| –
| –
| –
| –
| –
| –
| 2
| 3
| 5
| 7
| 9
| {{background color|lightgray|'''10'''}}
| 9
| 9
| 9
| 8
| 8
| 8
| 8
| 8
| 8
| 8

|-
! 20
! [[Mississippi|MS]]
| –
| –
| –
| –
| 1
| 2
| 4
| 5
| 5
| 6
| 7
| 7
| {{background color|lightgray|'''8'''}}
| {{background color|lightgray|'''8'''}}
| 7
| 7
| 6
| 5
| 5
| 5
| 5
| 4
| 4
|4
|-
! 24
! [[Missouri|MO]]
| –
| –
| –
| –
| 1
| 2
| 5
| 7
| 9
| 13
| 14
| 15
| {{background color|lightgray|'''16'''}}
| {{background color|lightgray|'''16'''}}
| 13
| 13
| 11
| 10
| 10
| 9
| 9
| 9
| 8
|8
|-
! 41
! [[Montana|MT]]
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| 1
| 1
| {{background color|lightgray|'''2'''}}
| {{background color|lightgray|'''2'''}}
| {{background color|lightgray|'''2'''}}
| {{background color|lightgray|'''2'''}}
| {{background color|lightgray|'''2'''}}
| {{background color|lightgray|'''2'''}}
| {{background color|lightgray|'''2'''}}
| 1
| 1
| 1
| {{background color|lightgray|'''2'''}}

|-
! 37
! [[Nebraska|NE]]
| –
| –
| –
| –
| –
| –
| –
| –
| –
| 1
| 3
| {{background color|lightgray|'''6'''}}
| {{background color|lightgray|'''6'''}}
| {{background color|lightgray|'''6'''}}
| 5
| 4
| 4
| 3
| 3
| 3
| 3
| 3
| 3
|3
|-
! 36
! [[Nevada|NV]]
| –
| –
| –
| –
| –
| –
| –
| –
| –
| 1
| 1
| 1
| 1
| 1
| 1
| 1
| 1
| 1
| 1
| 2
| 2
| 3
| {{background color|lightgray|'''4'''}}
|{{background color|lightgray|'''4'''}}

|-
! 9
! [[New Hampshire|NH]]
| 3
| 4
| 5
| {{background color|lightgray|'''6'''}}
| {{background color|lightgray|'''6'''}}
| 5
| 4
| 3
| 3
| 3
| 2
| 2
| 2
| 2
| 2
| 2
| 2
| 2
| 2
| 2
| 2
| 2
| 2
|2
|-
! 3
! [[New Jersey|NJ]]
| 4
| 5
| 6
| 6
| 6
| 6
| 5
| 5
| 5
| 7
| 7
| 8
| 10
| 12
| 14
| 14
| 14
| {{background color|lightgray|'''15'''}}
| {{background color|lightgray|'''15'''}}
| 14
| 13
| 13
| 12
|12
|-
! 47
! [[New Mexico|NM]]
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| 1
| 1
| 2
| 2
| 2
| 2
| {{background color|lightgray|'''3'''}}
| {{background color|lightgray|'''3'''}}
| {{background color|lightgray|'''3'''}}
| {{background color|lightgray|'''3'''}}
|{{background color|lightgray|'''3'''}}

|-
! 11
! [[New York (state)|NY]]
| 6
| 10
| 17
| 27
| 34
| 40
| 34
| 33
| 31
| 33
| 34
| 34
| 37
| 43
| {{background color|lightgray|'''45'''}}
| {{background color|lightgray|'''45'''}}
| 43
| 41
| 39
| 34
| 31
| 29
| 27
| 26

|-
! 12
! [[North Carolina|NC]]
| 5
| 10
| 12
| 13
| 13
| 13
| 9
| 8
| 7
| 8
| 9
| 9
| 10
| 10
| 11
| 12
| 12
| 11
| 11
| 11
| 12
| 13
| 13
| {{background color|lightgray|'''14'''}}

|-
! 39
! [[North Dakota|ND]]
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| 1
| 2
| {{background color|lightgray|'''3'''}}
| 2
| 2
| 2
| 2
| 1
| 1
| 1
| 1
| 1
|1
|-
! 17
! [[Ohio|OH]]
| –
| –
| 1
| 6
| 14
| 19
| 21
| 21
| 19
| 20
| 21
| 21
| 21
| 22
| {{background color|lightgray|'''24'''}}
| 23
| 23
| {{background color|lightgray|'''24'''}}
| 23
| 21
| 19
| 18
| 16
| 15

|-
! 46
! [[Oklahoma|OK]]
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| 8
| {{background color|lightgray|'''9'''}}
| 8
| 6
| 6
| 6
| 6
| 6
| 5
| 5
|5
|-
! 33
! [[Oregon|OR]]
| –
| –
| –
| –
| –
| –
| –
| –
| 1
| 1
| 1
| 2
| 2
| 3
| 3
| 4
| 4
| 4
| 4
| 5
| 5
| 5
| 5
| {{background color|lightgray|'''6'''}}

|-
! 2
! [[Pennsylvania|PA]]
| 8
| 13
| 18
| 23
| 26
| 28
| 24
| 25
| 24
| 27
| 28
| 30
| 32
| {{background color|lightgray|'''36'''}}
| 34
| 33
| 30
| 27
| 25
| 23
| 21
| 19
| 18
| 17

|-
! 13
! [[Rhode Island|RI]]
| 1
| 2
| 2
| 2
| 2
| 2
| 2
| 2
| 2
| 2
| 2
| 2
| 2
| {{background color|lightgray|'''3'''}}
| 2
| 2
| 2
| 2
| 2
| 2
| 2
| 2
| 2
| 2

|-
! 8
! [[South Carolina|SC]]
| 5
| 6
| 8
| {{background color|lightgray|'''9'''}}
| {{background color|lightgray|'''9'''}}
| {{background color|lightgray|'''9'''}}
| 7
| 6
| 4
| 5
| 7
| 7
| 7
| 7
| 6
| 6
| 6
| 6
| 6
| 6
| 6
| 6
| 7
| 7

|-
! 40
! [[South Dakota|SD]]
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| 2
| 2
| {{background color|lightgray|'''3'''}}
| 2
| 2
| 2
| 2
| 2
| 1
| 1
| 1
| 1
| 1

|-
! 16
! [[Tennessee|TN]]
| –
| –
| 3
| 6
| 9
| {{background color|lightgray|'''13'''}}
| 11
| 10
| 8
| 10
| 10
| 10
| 10
| 10
| 9
| 10
| 9
| 9
| 8
| 9
| 9
| 9
| 9
| 9

|-
! 28
! [[Texas|TX]]
| –
| –
| –
| –
| –
| –
| –
| 2
| 4
| 6
| 11
| 13
| 16
| 18
| 21
| 21
| 22
| 23
| 24
| 27
| 30
| 32
| 36
| {{background color|lightgray|'''38'''}}

|-
! 45
! [[Utah|UT]]
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| 1
| 2
| 2
| 2
| 2
| 2
| 2
| 3
| 3
| 3
| {{background color|lightgray|'''4'''}}
|{{background color|lightgray|'''4'''}}

|-
! 14
! [[Vermont|VT]]
| –
| 2
| 4
| {{background color|lightgray|'''6'''}}
| 5
| 5
| 4
| 3
| 3
| 3
| 2
| 2
| 2
| 2
| 1
| 1
| 1
| 1
| 1
| 1
| 1
| 1
| 1
|1
|-
! 10
! [[Virginia|VA]]
| 10
| 19
| 22
| {{background color|lightgray|'''23'''}}
| 22
| 21
| 15
| 13
| 11
| 9
| 10
| 10
| 10
| 10
| 9
| 9
| 10
| 10
| 10
| 10
| 11
| 11
| 11
|11
|-
! 42
! [[Washington (state)|WA]]
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| 2
| 3
| 5
| 6
| 6
| 7
| 7
| 7
| 8
| 9
| 9
| {{background color|lightgray|'''10'''}}
|{{background color|lightgray|'''10'''}}

|-
! 35
! [[West Virginia|WV]]
| –
| –
| –
| –
| –
| –
| –
| –
| –
| 3
| 4
| 4
| 5
| {{background color|lightgray|'''6'''}}
| {{background color|lightgray|'''6'''}}
| {{background color|lightgray|'''6'''}}
| {{background color|lightgray|'''6'''}}
| 5
| 4
| 4
| 3
| 3
| 3
| 2

|-
! 30
! [[Wisconsin|WI]]
| –
| –
| –
| –
| –
| –
| –
| 3
| 6
| 8
| 9
| 10
| {{background color|lightgray|'''11'''}}
| {{background color|lightgray|'''11'''}}
| 10
| 10
| 10
| 10
| 9
| 9
| 9
| 8
| 8
|8
|-
! 44
! [[Wyoming|WY]]
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| –
| {{backgroundcolor|lightgray|'''1'''}}
| {{background color|lightgray|'''1'''}}
| {{background color|lightgray|'''1'''}}
| {{background color|lightgray|'''1'''}}
| {{background color|lightgray|'''1'''}}
| {{backgroundcolor|lightgray|'''1'''}}
| {{backgroundcolor|lightgray|'''1'''}}
| {{backgroundcolor|lightgray|'''1'''}}
| {{backgroundcolor|lightgray|'''1'''}}
| {{backgroundcolor|lightgray|'''1'''}}
| {{backgroundcolor|lightgray|'''1'''}}
| {{backgroundcolor|lightgray|'''1'''}}
| {{backgroundcolor|lightgray|'''1'''}}
|}

==Changes per census==
===2010===
{{Main|2010 United States redistricting cycle}}
On December 21, 2010, the [[U.S. Census Bureau]] released its official apportionment results for congressional representation. The changes were in effect for the [[United States elections, 2012|U.S. elections in 2012]].<ref>{{cite news
 | url=https://www.census.gov/2010census/news/pdf/apport2010_table1.pdf
 | title=Apportionment Population and Number of Representatives, by State: 2010 Census
 | work=US Census
 | date=2010-12-21
 | access-date=2013-02-23
 | archive-url=https://web.archive.org/web/20150918231059/https://www.census.gov/2010census/news/pdf/apport2010_table1.pdf
 | archive-date=2015-09-18
 | url-status=dead}}
</ref>
{| class="wikitable"
|- style="vertical-align:bottom;"
! Gain four|| colspan="1" | Gain two|| colspan="1" |Gain one|| No change !! colspan="1" | Lose one|| |Lose two
|- style="vertical-align:top;"
|1. [[Texas]]
|1. [[Florida]]
|1. [[Arizona]]<br />2. [[Georgia (U.S. state)|Georgia]]<br />3. [[Nevada]]<br />4. [[South Carolina]]<br />5. [[Utah]]<br />6. [[Washington (state)|Washington]]
|(32 states)
|1. [[Illinois]]<br />2. [[Iowa]]<br />3. [[Louisiana]]<br />4. [[Massachusetts]]<br />5. [[Michigan]]<br />6. [[Missouri]]<br />7. [[New Jersey]]<br />8. [[Pennsylvania]]
|1. [[New York (state)|New York]]<br />2. [[Ohio]]
|-
! +4
! +2
! +6
!
! −8
! −4
|-
! colspan="3" | +12 seats gained total
!
! colspan="2" | −12 seats lost total
|-
! colspan="6" | [[File:2010 census reapportionment.svg|upright=1|thumb|center|Allocation of congressional districts after the [[2010 United States census|2010 U.S. census]]]]
|}

===2020===
{{Main|2020 United States redistricting cycle}}
Apportionment results were released on April 26, 2021:
{| class="wikitable"
|- style="vertical-align:bottom;"
! colspan="1" | Gain two|| colspan="1" |Gain one|| No change !! colspan="1" | Lose one
|- style="vertical-align:top;"
|1. Texas
|1. Colorado<br>2. Florida<br>3. Montana<br>4. North Carolina<br>5. Oregon
|(37 states)
|1. California<br>2. Illinois<br>3. Michigan<br>4. New York<br>5. Ohio<br>6. Pennsylvania<br>7. West Virginia
|-
! +2
! +5
!
! −7
|-
! colspan="2" |+7 seats gained total
!
! −7 seats lost total
|-
! colspan="4" |[[File:2020 census reapportionment.svg|upright=1|thumb|center|[[Reapportionment|Allocation of congressional districts]] in the [[United States House of Representatives|House of Representatives]] after the [[2020 United States census|2020 U.S. census]]]]
|}

== List of apportionments ==
The size of the [[United States House of Representatives|U.S. House of Representatives]] has increased and decreased as follows:<ref>[http://www.thirty-thousand.org/pages/QHA-02.htm The Size of the U. S. House of Representatives and its Constituent State Delegations], thirty-thousand.org.</ref>

{| class="wikitable sortable"
! width=130 | Effective date
! width=50 | Size
! width=35 | Change
! Legal provision
! Reason and/or comments

|-
| March 4, 1789
| style="text-align:center" | 59
| style="text-align:center" data-sort-value="0" | n/a
| rowspan=3 data-sort-value="0" | [[Article One of the United States Constitution#Clause 3: Apportionment of Representatives and taxes|Const. Art. I, § 2, cl. 3]]
| Seats apportioned by the Constitution based on population estimates made by the [[Philadelphia Convention]]. Only 11 of the original 13 states had ratified the Constitution by this time.

|-
| November 21, 1789
| style="text-align:center" | 64
| style="text-align:center" data-sort-value="5" | {{increase}} 5
| [[North Carolina]] ratified the Constitution with the seats apportioned by the Constitution.

|-
| May 29, 1790
| style="text-align:center" | 65
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| [[Rhode Island]] ratified the Constitution with the seat apportioned by the Constitution.

|-
| March 4, 1791
| style="text-align:center;" | 67
| style="text-align:center" data-sort-value="2" | {{increase}} 2
| rowspan=2 data-sort-value="01-191" | {{USStat|1|191}}
| [[Vermont]] admitted.

|-
| June 1, 1792
| style="text-align:center;" | 69
| style="text-align:center" data-sort-value="2" | {{increase}} 2
| [[Kentucky]] admitted.

|-
| March 4, 1793
| style="text-align:center" | 105
| style="text-align:center" data-sort-value="36" | {{increase}} 36
| data-sort-value="01-253" | {{USStat|1|253}} ([[Apportionment Act of 1792]])
| Apportionment following the [[1790 United States census|first census (1790)]]. First to use the [[D'Hondt method#Jefferson and D'Hondt|Jefferson method]].

|-
| June 1, 1796
| style="text-align:center" | 106
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="01-491" | {{USStat|1|491}}
| [[Tennessee]] admitted.

|-
| March 1, 1803
| style="text-align:center" | 107
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="02-175" | {{USStat|2|175}}
| [[Ohio]] admitted.

|-
| March 4, 1803
| style="text-align:center" | 142
| style="text-align:center" data-sort-value="35" | {{increase}} 35
| data-sort-value="02-128" | {{USStat|2|128}}
| Apportionment following the [[1800 United States census|second census (1800)]].

|-
| April 30, 1812
| style="text-align:center" | 143
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="02-703" | {{USStat|2|703}}
| [[Louisiana]] admitted.

|-
| March 4, 1813
| style="text-align:center" | 182
| style="text-align:center" data-sort-value="39" | {{increase}} 39
| data-sort-value="02-669" | {{USStat|2|669}}
| Apportionment following the [[1810 United States census|third census (1810)]].

|-
| December 11, 1816
| style="text-align:center" | 183
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="03-290" | {{USStat|3|290}}
| [[Indiana]] admitted.

|-
| December 10, 1817
| style="text-align:center" | 184
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="03-349" | {{USStat|3|349}}
| [[Mississippi]] admitted.

|-
| December 3, 1818
| style="text-align:center" | 185
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="03-430" | {{USStat|3|430}}
| [[Illinois]] admitted.

|-
| December 14, 1819
| style="text-align:center" rowspan=2 | 186
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="03-492" | {{USStat|3|492}}
| [[Alabama]] admitted.

|-
| March 15, 1820
| style="text-align:center" data-sort-value="0" | {{steady}}
| data-sort-value="03-555" | {{USStat|3|555}}
| [[Maine]] admitted, 7 seats transferred from [[Massachusetts]].

|-
| August 10, 1821
| style="text-align:center" | 187
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="03-547" | {{USStat|3|547}}
| [[Missouri]] admitted.

|-
| March 4, 1823
| style="text-align:center" | 213
| style="text-align:center" data-sort-value="26" | {{increase}} 26
| data-sort-value="03-651" | {{USStat|3|651}}
| Apportionment following the [[1820 United States census|fourth census (1820)]].

|-
| March 4, 1833
| style="text-align:center" | 240
| style="text-align:center" data-sort-value="27" | {{increase}} 27
| data-sort-value="04-516" | {{USStat|4|516}}
| Apportionment following the [[1830 United States census|fifth census (1830)]].

|-
| June 15, 1836
| style="text-align:center" | 241
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="05-051" | {{USStat|5|51}}
| [[Arkansas]] admitted.

|-
| January 26, 1837
| style="text-align:center" | 242
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="05-050" | {{USStat|5|50}}<!-- Correct even though it appears in USStat *before* Arkansas. AR's act of admission was unconditional, so it legally received its House seat the moment the act was signed (June 15, 1836). Michigan's admission, however, was conditioned on its accepting Congress' award of the disputed Toledo Strip to Ohio in exchange for the Upper Peninsula; it did NOT gain its seat until the presidential proclamation called for by this section was issued (January 26, 1837). This is also why AR is considered to have been admitted first (25th state vs. MI 26th), even though (per the later North & South Dakota precedent) MI's act of admission is deemed to have become law before AR's. -->
| [[Michigan]] admitted.

|-
| March 4, 1843
| style="text-align:center" | 223
| style="text-align:center" data-sort-value="-19" | {{decrease}} 19
| data-sort-value="05-491" | {{USStat|5|491}}
| Apportionment following the [[1840 United States census|sixth census (1840)]]. First to use the [[Sainte-Laguë method|Webster method]]. Became the '''only time the size of the House was reduced''', except for the minor readjustments in 1863 and 1963.

|-
| March 3, 1845
| style="text-align:center" | 224
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="05-743" | {{USStat|5|743}}
| [[Florida]] admitted.

|-
| December 29, 1845
| style="text-align:center" | 226
| style="text-align:center" data-sort-value="2" | {{increase}} 2
| data-sort-value="05-798" | {{USStat|5|798}}
| [[Texas Annexation|Texas annexed]] and admitted.

|-
| December 28, 1846
| style="text-align:center" | 228
| style="text-align:center" data-sort-value="2" | {{increase}} 2
| data-sort-value="05-743" | {{USStat|5|743}}<br/>{{USStat|9|52}}
| [[Iowa]] admitted.

|-
| May 29, 1848
| style="text-align:center" | 230
| style="text-align:center" data-sort-value="2" | {{increase}} 2
| data-sort-value="09-058" | {{USStat|9|58}}<br/>{{USStat|9|235}}
| [[Wisconsin]] admitted.

|-
| March 4, 1849
| style="text-align:center" | 231
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="09-235" | {{USStat|9|235}}
| Additional seat apportioned to Wisconsin.

|-
| September 9, 1850
| rowspan="2" style="text-align:center" | 233
| style="text-align:center" data-sort-value="2" | {{increase}} 2
| data-sort-value="09-452" | {{USStat|9|452}}
| [[California]] admitted.

|-
| rowspan=2 | March 4, 1853
| style="text-align:center" data-sort-value="0" | {{steady}}
| data-sort-value="09-432.1853" | {{USStat|9|432}}
| Apportionment following the [[1850 United States census|seventh census (1850)]]. First to use the [[Alexander Hamilton|Hamilton]]/[[Samuel Finley Vinton|Vinton]] ([[Largest remainder method|largest remainder]]) method.

|-
| style="text-align:center" | 234
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="10-025" | {{USStat|10|25}}
| Additional seat apportioned to California{{efn | The 1850 Apportionment bill provided a method to be used in future reapportionments, as well as establishing the then-current 233 as the number of seats to be apportioned after future censuses. Due to census returns being incomplete in California, an additional act provided that California retain the same representation it had when admitted, until a new census could be taken. California would otherwise have lost one seat, and so the total number of seats was increased by one to 234.}}

|-
| May 11, 1858
| style="text-align:center" | 236
| style="text-align:center" data-sort-value="2" | {{increase}} 2
| data-sort-value="11-166" | {{USStat|11|166}}
| [[Minnesota]] admitted.

|-
| February 14, 1859
| style="text-align:center" | 237
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="11-383" | {{USStat|11|383}}
| [[Oregon]] admitted.

|-
| January 29, 1861
| style="text-align:center" | 238
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="12-126" | {{USStat|12|126}}
| [[Kansas]] admitted

|-
| June 2, 1862
| style="text-align:center" | 239
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="12-411" | {{USStat|12|411}}
| California apportioned an extra seat.

|-
| rowspan= 2 | March 4, 1863
| style="text-align:center" | 233
| style="text-align:center" data-sort-value="-6" | {{decrease}} 6
| data-sort-value="09-432.1863" | {{USStat|9|432}}
| Apportionment following the [[1860 United States census|eighth census (1860)]], in accordance with the 1850 act, which provided for an apportionment of 233 seats.

|-
| style="text-align:center" rowspan=2 | 241
| style="text-align:center" data-sort-value="8" | {{increase}} 8
| data-sort-value="12-353" | {{USStat|12|353}}
| Supplemental apportionment of 8 seats (1 each for Pennsylvania, Ohio, Kentucky, Illinois, Iowa, Minnesota, Vermont, and Rhode Island), for an overall increase of 2 seats in the 38th Congress.

|-
| June 20, 1863
| style="text-align:center" data-sort-value="0" | {{steady}}
| data-sort-value="12-633" | {{USStat|12|633}}
| [[West Virginia]] [[West Virginia#Separation from Virginia|admitted]], three seats transferred from [[Virginia]].

|-
| October 31, 1864
| style="text-align:center" | 242
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="13-032" | {{USStat|13|32}}
| [[Nevada]] admitted

|-
| March 1, 1867
| style="text-align:center" | 243
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="14-391" | {{USStat|14|391}}
| [[Nebraska]] admitted

|-
| rowspan=2 | March 4, 1873
| style="text-align:center" | 283
| style="text-align:center" data-sort-value="40" | {{increase}} 40
| data-sort-value="17-028" | {{USStat|17|28}}
| Apportionment following the [[1870 United States census|ninth census (1870)]], replacing the 1850 act

|-
| style="text-align:center" | 292
| style="text-align:center" data-sort-value="9" | {{increase}} 9
| data-sort-value="17-192" | {{USStat|17|192}}
| Supplemental apportionment added one seat each for nine states

|-
| August 1, 1876
| style="text-align:center" | 293
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="13-034" | {{USStat|13|34}}
| [[Colorado]] admitted

|-
| March 4, 1883
| style="text-align:center" | 325
| style="text-align:center" data-sort-value="32" | {{increase}} 32
| data-sort-value="22-005" | {{USStat|22|5}}
| Apportionment following the [[1880 United States census|tenth census (1880)]].

|-
| November 2, 1889
| style="text-align:center" | 328
| style="text-align:center" data-sort-value="3" | {{increase}} 3
| data-sort-value="25-679" | {{USStat|25|679}}
| [[North Dakota|North]] and [[South Dakota|South]] Dakota admitted, with one and two seats respectively.

|-
| November 8, 1889
| style="text-align:center" | 329
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="25-679" | {{USStat|25|679}}
| [[Montana]] admitted.

|-
| November 11, 1889
| style="text-align:center" | 330
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="25-679" | {{USStat|25|679}}
| [[Washington (state)|Washington]] admitted.

|-
| July 3, 1890
| style="text-align:center" | 331
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="26-215" | {{USStat|26|215}}
| [[Idaho]] admitted.

|-
| July 10, 1890
| style="text-align:center" | 332
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="26-222" | {{USStat|26|222}}
| [[Wyoming]] admitted.

|-
| March 4, 1893
| style="text-align:center" | 356
| style="text-align:center" data-sort-value="24" | {{increase}} 24
| data-sort-value="26-735" | {{USStat|26|735}}
| Apportionment following the [[1890 United States census|eleventh census (1890)]].

|-
| January 4, 1896
| style="text-align:center" | 357
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="28-109" | {{USStat|28|109}}
| [[Utah]] admitted.

|-
| March 4, 1903
| style="text-align:center" | 386
| style="text-align:center" data-sort-value="29" | {{increase}} 29
| data-sort-value="31-733" | {{USStat|31|733}}
| Apportionment following the [[1900 United States census|twelfth census (1900)]]

|-
| November 16, 1907
| style="text-align:center" | 391
| style="text-align:center" data-sort-value="5" | {{increase}} 5
| data-sort-value="34-271" | {{USStat|34|271}}
| [[Oklahoma]] admitted

|-
| January 6, 1912
| style="text-align:center" | 393
| style="text-align:center" data-sort-value="2" | {{increase}} 2
| rowspan="2" data-sort-value="37-014" | {{USStat|37|39}}, incorporating {{USStat|36|557}}
| [[New Mexico]] admitted

|-
| February 14, 1912
| style="text-align:center" | 394
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| [[Arizona]] admitted

|-
| March 4, 1913
| rowspan="4" style="text-align:center" | 435
| style="text-align:center" data-sort-value="41" | {{increase}} 41
| data-sort-value="37-013" | {{USStat|37|13}} ([[Apportionment Act of 1911]], §§1–2)
| Apportionment following the [[1910 United States census|thirteenth census (1910)]]. Process returned to the Webster method.

|-
| March 4, 1933
| rowspan="3" style="text-align:center" data-sort-value="0" | {{steady}}
| data-sort-value="46-026" | {{USStat|46|26}} ([[Reapportionment Act of 1929]])
| Apportionment following the [[1930 United States census|fifteenth census (1930)]].{{efn | Congress failed to reapportion in 1923, following the [[1920 United States census|fourteenth census (1920)]].}} The size of the House became permanently capped at 435 seats under the Reapportionment Act of 1929.

|-
| January 3, 1943
| data-sort-value="54-162" | {{USStat|46|26}} ([[Reapportionment Act of 1929]])<br/>{{USStat|54|162}}
| Apportionment following the [[1940 United States census|sixteenth census (1940)]]. First to use the [[Huntington–Hill method]]. 
|-
| January 3, 1953
| data-sort-value="55-761" | {{USStat|55|761}}
| Apportionment following the [[1950 United States census|seventeenth census (1950)]]{{efn | {{USPL|77|291}} amended section 22 of the [[Reapportionment Act of 1929]] by wholly replacing its text.}}

|-
| January 3, 1959
| style="text-align:center" | 436
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="72-345" | {{USStat|72|345}}
| [[Alaska]] admitted.

|-
| August 21, 1959
| style="text-align:center" | 437
| style="text-align:center" data-sort-value="1" | {{increase}} 1
| data-sort-value="73-008.8" | {{USStat|73|8}}, §8
| [[Hawaii]] admitted.

|-
| [[1960 United States redistricting cycle|January 3, 1963]]
| rowspan="7" style="text-align:center" | 435
| style="text-align:center" data-sort-value="-2" | {{decrease}} 2
| data-sort-value="73-008" | {{USStat|72|345}}<br/>{{USStat|73|8}}<br/>{{UnitedStatesCode|2|2a}}
| Apportionment following the [[1960 United States census|eighteenth census (1960)]]{{efn | The [[Reapportionment Act of 1929]] stated that the "then existing number of Representatives" would be apportioned after each census, which would have dictated an apportionment of 437 seats, but the [[Alaska Statehood Act]] and [[Hawaii Admission Act]] explicitly stated that the new seats were temporary increases. Both acts included the phrasing "That such temporary increase in the membership shall not operate to either increase or decrease the permanent membership of the House of Representatives as prescribed in the [[Apportionment Act of 1911|Act of August 8, 1911]] ({{USStat|37|13}}) nor shall such temporary increase affect the basis of apportionment established by the Act of November 15, 1941 ({{USStat|55|761}}; {{UnitedStatesCode|2|2a}}), for the [[Eighty-third Congress]] and each Congress thereafter."<ref>See, e.g., section 8 of the [[Hawaii Admission Act]], {{USStat|73|8}}.</ref>}}

|-
| [[1970 United States redistricting cycle|January 3, 1973]]
| rowspan="6" style="text-align:center" data-sort-value="0" | {{steady}}
| rowspan="6" data-sort-value="99-1973" | {{UnitedStatesCode|2|2a}}
| Apportionment following the [[1970 United States census|nineteenth census (1970)]].

|-
| [[1980 United States redistricting cycle|January 3, 1983]]
| Apportionment following the [[1980 United States census|twentieth census (1980)]].

|-
| [[1990 United States redistricting cycle|January 3, 1993]]
| Apportionment following the [[1990 United States census|twenty-first census (1990)]].

|-
| [[2000 United States redistricting cycle|January 3, 2003]]
| Apportionment following the [[2000 United States census|twenty-second census (2000)]].

|-
| [[2010 United States redistricting cycle|January 3, 2013]]
| Apportionment following the [[2010 United States census|twenty-third census (2010)]].

|-
| [[2020 United States redistricting cycle|January 3, 2023]]
| Apportionment following the [[2020 United States census|twenty-fourth census (2020)]].
|}

==See also==
* [[List of U.S. states by population]]
* [[List of U.S. states by historical population]] (tables of state populations since 1790)
* [[Electoral vote changes between United States presidential elections]]

==Notes==
* Delegate counts in ''italics'' represent temporary counts assigned by Congress until the next decennial census or by the U.S. Constitution in 1789 until the first U.S. census.
* Elections held in the year of a census use the apportionment determined by the previous census.
{{notelist}}

;Citations 
{{Reflist|2}}

==References==
* {{Cite book|last1=Balinski |first1=Michael L. |last2=Young |first2=H. Peyton |year=1982 |title=Fair Representation: Meeting the Ideal of One Man, One Vote |place=New Haven, CT |publisher=Yale University Press |url=https://books.google.com/books?id=eBFNzSeAv_sC |isbn=0-8157-0090-3 }}
* {{Cite book|last=Foster |first=Robert |year=1895 |title=Commentaries on the Constitution of the United States: Historical and Judicial |volume=1 |place=Boston |publisher=The Boston Book Co. |pages=329–446 |url=https://books.google.com/books?id=Rd49AAAAIAAJ }}
* {{Cite book|last1=Hamilton |first1=Alexander |author-link=Alexander Hamilton |last2=Madison |first2=James |author2-link=James Madison |last3=Jay |first3=John |author3-link=John Jay |year=1831 |title=The Federalist |place=Hallowell |publisher=Glazier, Masters & Co. |url=https://archive.org/details/federalistonnew01jaygoog |isbn=0-8239-5735-7 }}
* {{Cite journal|last=Edelman|first=Paul H.|title=Getting the Math Right: Why California Has Too Many Seats in the House of Representatives|journal=Vanderbilt Law Review|volume=102|issue=March|page=297|publisher=Vanderbilt University|location=Nashville|year=2006}}
* {{Cite journal |doi=10.2307/3234988 |author1=Kromkowski, Charles A. |author2=Kromkowski, John A. |title=Why 435? A Question of Political Arithmetic |journal=Polity |volume=24 |issue=Fall 1991 |pages=129–145 |url=http://www.thirty-thousand.org/documents/Kromkowski_Fall1991.pdf |year =1991 |jstor=3234988 |s2cid=155209561 |access-date=2013-10-17}}
* {{Cite journal|last=Agnew|first=Robert A.|title=Optimal Congressional Apportionment|journal=American Mathematical Monthly|volume=115|issue=April|pages=297–303|publisher=Mathematical Association of America|year=2008|doi=10.1080/00029890.2008.11920530|jstor=27642473 |s2cid=14596741|url=http://www.raagnew.com/uploads/5/7/1/7/57174385/optimal_congressional_apportionment.pdf}}

==Further reading==
* {{Cite journal|last=Stinebrickner-Kauffman|first=Taren|title=Counting Matters: Prison Inmates, Population Bases, and "One Person, One Vote"|journal=Virginia Journal of Social Policy & the Law|volume=11|issue=Winter|page=229|location=Chicago|year=2004}}

==External links==
* [https://www.census.gov/topics/public-sector/congressional-apportionment.html Congressional Apportionment by the U.S. Census Bureau]

{{Constitution of the United States}}
{{United States Congress|membersandleaders}}
{{Redistricting (US)}}
{{USRedistrictinglaw}}

{{DEFAULTSORT:United States Congressional Apportionment}}
[[Category:Demographics of the United States|Congressional apportionment]]
[[Category:United States House of Representatives|Apportionment]]
[[Category:Terminology of the United States Congress|Congressional apportionment]]
[[Category:United States congressional districts|Congressional apportionment]]
[[Category:Redistricting in the United States]]
[[Category:Apportionment by country]]