United States congressional apportionment

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 by which seats in the United States House of Representatives are distributed among the 50 states according to the most recent decennial census mandated by the United States Constitution. After each state is guaranteed a minimum of one seat in the House, most states are then apportioned a number of additional seats which roughly corresponds to its share of the aggregate population of the 50 states. Every state is constitutionally guaranteed two seats in the 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 admitted into the Union. The Huntington–Hill method of equal proportions has been used to distribute the seats among the states since the 1940 census reapportionment. The Constitution itself makes no mention of districts.

The U.S. Constitution does not specify how apportionment is to be conducted and multiple methods have been developed and utilized since the Article's inception, such as the Jefferson, Hamilton and Webster methods. The Jefferson method was first utilized in 1792 after the first decennial census was conducted in 1790 but was abandoned in 1840 as it favoured larger states such as Virginia, Thomas Jefferson's home state and the most influential state at the time. Hamilton's method was used intermittently for the next half-century and was eventually replaced by Webster's as the Hamilton method resulted in population paradoxes when the House size increased. After the House size and number of congressional districts were fixed in 1941, the Huntington–Hill method became the official method of apportionment and was used in the 2020 apportionment and redistricting cycle. The current method solves many of the issues concerning previous methods; however, it still violates the "one person, one vote" rule established in Wesberry v. Sanders (1964) due to systematic bias which gives more representation and power to small states than to residents of large states.

These methods have been the subject of debate for over 200 years as losing or gaining a seat affects representation which is the source of political power. Congressional districts are subject to the Equal Protection Clause and it is expected that they apportion congressional districts closer to mathematical equality than state legislative districts. The U.S Supreme Court in Karcher v. Daggett (1983) rejected New Jersey's congressional redistricting plans due to a deviation of less than 1%.

Article One, Section 2, Clause 3 of the United States Constitution initially provided:

The phrase "all other persons" refers to slaves, a word not used in the Constitution until the Thirteenth Amendment.

Following the end of the Civil War, the first of those provisions was superseded by Section 2 of the Fourteenth Amendment:

The phrase "counting the whole number of persons in each State" has traditionally been understood to include non-citizens for purposes of apportionment.

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 U.S. Electoral College. Under 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 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 congressional districts—geographical areas within the state of approximately equal population—in a process called redistricting.

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.

Number of members

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 set at 435. There are an additional five 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, and the U.S. Virgin Islands. Puerto Rico also elects a 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 . 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 year

! Source

! Avg. constituents per member

| 1793

| nowrap | 1790 census

| 34,436

| 1803

| 1800 census

| 34,609

| 1813

| 1810 census

| 36,377

| 1823

| 1820 census

| 42,124

| 1833

| 1830 census

| 49,712

| 1843

| 1840 census

| 71,338

| 1853

| 1850 census

| 93,020

| 1863

| 1860 census

| 122,614

| 1873

| 1870 census

| 130,533

| 1883

| 1880 census

| 151,912

| 1893

| 1890 census

| 173,901

| 1903

| 1900 census

| 193,167

| 1913

| 1910 census

| 210,583

| 1923

| 1920 census

| 243,728

| 1933

| 1930 census

| 280,675

| 1943

| 1940 census

| 301,164

| 1953

| 1950 census

| 334,587

| 1963

| 1960 census

| 410,481

| 1973

| 1970 census

| 469,088

| 1983

| 1980 census

| 510,818

| 1993

| 1990 census

| 571,477

| 2003

| 2000 census

| 646,946

| 2013

| 2010 census

| 709,760

| 2023

| 2020 census

| 761,169

| colspan="3" |

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 Constitutional Convention (one representative for every 40,000) was inadequate and supported an alteration to reduce that number to 30,000. This was the only time that Washington pronounced an opinion on any of the actual issues debated during the entire convention. 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 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.

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,

Madison argued against the assumption that more is better:

</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 mth 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 A1 corresponds to the largest state, California, which is allocated seat 51. After being allocated its 2nd seat, its priority value decreases to its A2 value, which is reordered to a position back in line. The 52nd seat goes to Texas, the 2nd largest state, because its A1 priority value is larger than the An of any other state. However, the 53rd seat goes back to California because its A2 priority value is larger than the An of any other state. The 54th seat goes to New York because its A1 priority value is larger than the An 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 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.

The 2020 census ranking of priority values 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.

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.

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" | Statehood order

! Census

! style="padding:0;" | Const.

! 1st

! 2nd

! 3rd

! 4th

! 5th

! 6th

! 7th

! 8th

! 9th

! 10th

! 11th

! 12th

! 13th

! style="padding:0;" | 15th

! 16th

! 17th

! 18th

! 19th

! 20th

! 21st

! 22nd

! 23rd

! 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" |

! 22

! AL

| –

| 3

| 5

| 7

| 6

| 8

| 9

| 8

| 7

! 49

! AK

| –

! 48

! AZ

| –

| 1

| 2

| 3

| 4

| 5

| 6

| 8

! 25

! AR

| –

| 1

| 2

| 3

| 4

| 5

| 6

| 4

! 31

! CA

| –

| 2

| 3

| 4

| 6

| 7

| 8

| 11

| 20

| 23

| 30

| 38

| 43

| 45

| 52

! 38

! CO

| –

| 1

| 2

| 3

| 4

| 5

| 6

| 7

! 5

! CT

| 5

| 6

| 4

| 5

| 6

| 5

! 1

! DE

| 1

! 27

! FL

| –

| 1

| 2

| 3

| 4

| 5

| 6

| 8

| 12

| 15

| 19

| 23

| 25

| 27

! 4

! GA

| 3

| 2

| 4

| 6

| 7

| 9

| 8

| 7

| 9

| 10

| 11

| 12

| 10

| 11

| 13

! 50

! HI

| –

! 43

! ID

| –

| 1

! 21

! IL

| –

| 1

| 3

| 7

| 9

| 14

| 19

| 20

| 22

| 25

| 26

| 25

| 24

| 22

| 20

| 19

| 18

| 17

! 19

! IN

| –

| 3

| 7

| 10

| 11

| 12

| 11

| 10

| 9

! 29

! IA

| –

| 2

| 6

| 9

| 8

| 7

| 6

| 5

| 4

! 34

! KS

| –

| 1

| 3

| 7

| 6

| 5

| 4

! 15

! KY

| –

| 2

| 6

| 10

| 12

| 10

| 9

| 10

| 11

| 9

| 8

| 7

| 6

! 18

! LA

| –

| 1

| 3

| 4

| 5

| 6

| 7

| 6

! 23

! ME

| –

| 7

| 6

| 5

| 4

| 3

| 2

! 7

! MD

| 6

| 8

| 6

| 5

| 6

| 7

| 8

! 6

! MA

| 8

| 14

| 17

| 13

| 12

| 10

| 11

| 10

| 11

| 12

| 13

| 14

| 16

| 15

| 14

| 12

| 11

| 10

| 9

! 26

! MI

| –

| 3

| 4

| 6

| 9

| 11

| 12

| 13

| 17

| 18

| 16

| 15

| 14

| 13

! 32

! MN

| –

| 2

| 3

| 5

| 7

| 9

| 8

! 20

! MS

| –

| 1

| 2

| 4

| 5

| 6

| 7

| 6

| 5

| 4

! 24

! MO

| –

| 1

| 2

| 5

| 7

| 9

| 13

| 14

| 15

| 13

| 11

| 10

| 9

| 8

! 41

! MT

| –

| 1

! 37

! NE

| –

| 1

| 3

| 5

| 4

| 3

! 36

! NV

| –

| 1

| 2

| 3

! 9

! NH

| 3

| 4

| 5

| 4

| 3

| 2

! 3

! NJ

| 4

| 5

| 6

| 5

| 7

| 8

| 10

| 12

| 14

| 13

| 12

|12

! 47

! NM

| –

| 1

| 2

! 11

! NY

| 6

| 10

| 17

| 27

| 34

| 40

| 34

| 33

| 31

| 33

| 34

| 37

| 43

| 41

| 39

| 34

| 31

| 29

| 27

| 26

! 12

! NC

| 5

| 10

| 12

| 13

| 9

| 8

| 7

| 8

| 9

| 10

| 11

| 12

| 11

| 12

| 13

! 39

! ND

| –

| 1

| 2

| 1

! 17

! OH

| –

| 1

| 6

| 14

| 19

| 21

| 19

| 20

| 21

| 22

| 23

| 21

| 19

| 18

| 16

| 15

! 46

! OK

| –

| 8

| 6

| 5

! 33

! OR

| –

| 1

| 2

| 3

| 4

| 5

! 2

! PA

| 8

| 13

| 18

| 23

| 26

| 28

| 24

| 25

| 24

| 27

| 28

| 30

| 32

| 34

| 33

| 30

| 27

| 25

| 23

| 21

| 19

| 18

| 17

! 13

! RI

| 1

| 2

! 8

! SC

| 5

| 6

| 8

| 7

| 6

| 4

| 5

| 7

| 6

| 7

! 40

! SD

| –

| 2

| 1

! 16

! TN

| –

| 3

| 6

| 9

| 11

| 10

| 8

| 10

| 9

| 10

| 9

| 8

| 9

! 28

! TX

| –

| 2

| 4

| 6

| 11

| 13

| 16

| 18

| 21

| 22

| 23

| 24

| 27

| 30

| 32

| 36

! 45

! UT

| –

| 1

| 2

| 3

! 14

! VT

| –

| 2

| 4

| 5

| 4

| 3

| 2

| 1

! 10

! VA

| 10

| 19

| 22

| 21

| 15

| 13

| 11

| 9

| 10

| 9

| 10

| 11

|11

! 42

! WA

| –

| 2

| 3

| 5

| 6

| 7

| 8

| 9

! 35

! WV

| –

| 3

| 4

| 5

| 4

| 3

| 2

! 30

! WI

| –

| 3

| 6

| 8

| 9

| 10

| 9

| 8

! 44

! WY

| –

Changes per census

2010

On December 21, 2010, the U.S. Census Bureau released its official apportionment results for congressional representation. The changes were in effect for the U.S. elections in 2012.

{| 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 2. Georgia 3. Nevada 4. South Carolina 5. Utah 6. Washington

|(32 states)

|1. Illinois 2. Iowa 3. Louisiana 4. Massachusetts 5. Michigan 6. Missouri 7. New Jersey 8. Pennsylvania

|1. New York 2. Ohio

! +4

! +2

! +6

! −8

! −4

! colspan="3" | +12 seats gained total

! colspan="2" | −12 seats lost total

2020

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 2. Florida 3. Montana 4. North Carolina 5. Oregon

|(37 states)

|1. California 2. Illinois 3. Michigan 4. New York 5. Ohio 6. Pennsylvania 7. West Virginia

! +2

! +5

! −7

! colspan="2" |+7 seats gained total

! −7 seats lost total

The changes took effect in the U.S. elections in 2024.

List of apportionments

The size of the U.S. House of Representatives has increased and decreased as follows:

{| 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" | 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" | 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" | 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" | 2

| rowspan=2 data-sort-value="01-191" |

| Vermont admitted.

| June 1, 1792

| style="text-align:center;" | 69

| style="text-align:center" data-sort-value="2" | 2

| Kentucky admitted.

| March 4, 1793

| style="text-align:center" | 105

| style="text-align:center" data-sort-value="36" | 36

| data-sort-value="01-253" | (Apportionment Act of 1792)

| Apportionment following the first census (1790). First to use the Jefferson method.

| June 1, 1796

| style="text-align:center" | 106

| style="text-align:center" data-sort-value="1" | 1

| data-sort-value="01-491" |

| Tennessee admitted.

| March 1, 1803

| style="text-align:center" | 107

| style="text-align:center" data-sort-value="1" | 1

| data-sort-value="02-175" |

| Ohio admitted.

| March 4, 1803

| style="text-align:center" | 142

| style="text-align:center" data-sort-value="35" | 35

| data-sort-value="02-128" |

| Apportionment following the second census (1800).

| April 30, 1812

| style="text-align:center" | 143

| style="text-align:center" data-sort-value="1" | 1

| data-sort-value="02-703" |

| Louisiana admitted.

| March 4, 1813

| style="text-align:center" | 182

| style="text-align:center" data-sort-value="39" | 39

| data-sort-value="02-669" |

| Apportionment following the third census (1810).

| December 11, 1816

| style="text-align:center" | 183

| style="text-align:center" data-sort-value="1" | 1

| data-sort-value="03-290" |

| Indiana admitted.

| December 10, 1817

| style="text-align:center" | 184

| style="text-align:center" data-sort-value="1" | 1

| data-sort-value="03-349" |

| Mississippi admitted.

| December 3, 1818

| style="text-align:center" | 185

| style="text-align:center" data-sort-value="1" | 1

| data-sort-value="03-430" |

| Illinois admitted.

| December 14, 1819

| style="text-align:center" rowspan=2 | 186

| style="text-align:center" data-sort-value="1" | 1

| data-sort-value="03-492" |

| Alabama admitted.

| March 15, 1820

| style="text-align:center" data-sort-value="0" |

| data-sort-value="03-555" |

| Maine admitted, 7 seats transferred from Massachusetts.

| August 10, 1821

| style="text-align:center" | 187

| style="text-align:center" data-sort-value="1" | 1

| data-sort-value="03-547" |

| Missouri admitted.

| March 4, 1823

| style="text-align:center" | 213

| style="text-align:center" data-sort-value="26" | 26

| data-sort-value="03-651" |

| Apportionment following the fourth census (1820).

| March 4, 1833

| style="text-align:center" | 240

| style="text-align:center" data-sort-value="27" | 27

| data-sort-value="04-516" |

| Apportionment following the fifth census (1830).

| June 15, 1836

| style="text-align:center" | 241

| style="text-align:center" data-sort-value="1" | 1

| data-sort-value="05-051" |

| Arkansas admitted.

| January 26, 1837

| style="text-align:center" | 242

| style="text-align:center" data-sort-value="1" | 1

| data-sort-value="05-050" |

| Michigan admitted.

| March 4, 1843

| style="text-align:center" | 223

| style="text-align:center" data-sort-value="-19" | 19

| data-sort-value="05-491" |

| Apportionment following the sixth census (1840). First to use the 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" | 1

| data-sort-value="05-743" |

| Florida admitted.

| December 29, 1845

| style="text-align:center" | 226

| style="text-align:center" data-sort-value="2" | 2

| data-sort-value="05-798" |

| Texas annexed and admitted.

| December 28, 1846

| style="text-align:center" | 228

| style="text-align:center" data-sort-value="2" | 2

| data-sort-value="05-743" |

| Iowa admitted.

| May 29, 1848

| style="text-align:center" | 230

| style="text-align:center" data-sort-value="2" | 2

| data-sort-value="09-058" |

| Wisconsin admitted.

| March 4, 1849

| style="text-align:center" | 231

| style="text-align:center" data-sort-value="1" | 1

| data-sort-value="09-235" |

| Additional seat apportioned to Wisconsin.

| September 9, 1850

| rowspan="2" style="text-align:center" | 233

| style="text-align:center" data-sort-value="2" | 2

| data-sort-value="09-452" |

| California admitted.

| rowspan=2 | March 4, 1853

| style="text-align:center" data-sort-value="0" |

| data-sort-value="09-432.1853" |

| Apportionment following the seventh census (1850). First to use the Hamilton/Vinton (largest remainder) method.

| style="text-align:center" | 234

| style="text-align:center" data-sort-value="1" | 1

| data-sort-value="10-025" |

| Additional seat apportioned to California

| May 11, 1858

| style="text-align:center" | 236

| style="text-align:center" data-sort-value="2" | 2

| data-sort-value="11-166" |

| Minnesota admitted.

| February 14, 1859

| style="text-align:center" | 237

| style="text-align:center" data-sort-value="1" | 1

| data-sort-value="11-383" |

| Oregon admitted.

| January 29, 1861

| style="text-align:center" | 238

| style="text-align:center" data-sort-value="1" | 1

| data-sort-value="12-126" |

| Kansas admitted

| June 2, 1862

| style="text-align:center" | 239

| style="text-align:center" data-sort-value="1" | 1

| data-sort-value="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" | 6

| data-sort-value="09-432.1863" |

| Apportionment following the 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" | 8

| data-sort-value="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" |

| data-sort-value="12-633" |

| West Virginia admitted, three seats transferred from Virginia.

| October 31, 1864

| style="text-align:center" | 242

| style="text-align:center" data-sort-value="1" | 1

| data-sort-value="13-032" |

| Nevada admitted

| March 1, 1867

| style="text-align:center" | 243

| style="text-align:center" data-sort-value="1" | 1

| data-sort-value="14-391" |

| Nebraska admitted

| rowspan=2 | March 4, 1873

| style="text-align:center" | 283

| style="text-align:center" data-sort-value="40" | 40

| data-sort-value="17-028" |

| Apportionment following the ninth census (1870), replacing the 1850 act

| style="text-align:center" | 292

| style="text-align:center" data-sort-value="9" | 9

| data-sort-value="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" | 1

| data-sort-value="13-034" |

| Colorado admitted

| March 4, 1883

| style="text-align:center" | 325

| style="text-align:center" data-sort-value="32" | 32

| data-sort-value="22-005" |

| Apportionment following the tenth census (1880).

| November 2, 1889

| style="text-align:center" | 328

| style="text-align:center" data-sort-value="3" | 3

| data-sort-value="25-679" |

| North and 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" | 1

| data-sort-value="25-679" |

| Montana admitted.

| November 11, 1889

| style="text-align:center" | 330

| style="text-align:center" data-sort-value="1" | 1

| data-sort-value="25-679" |

| Washington admitted.

| July 3, 1890

| style="text-align:center" | 331

| style="text-align:center" data-sort-value="1" | 1

| data-sort-value="26-215" |

| Idaho admitted.

| July 10, 1890

| style="text-align:center" | 332

| style="text-align:center" data-sort-value="1" | 1

| data-sort-value="26-222" |

| Wyoming admitted.

| March 4, 1893

| style="text-align:center" | 356

| style="text-align:center" data-sort-value="24" | 24

| data-sort-value="26-735" |

| Apportionment following the eleventh census (1890).

| January 4, 1896

| style="text-align:center" | 357

| style="text-align:center" data-sort-value="1" | 1

| data-sort-value="28-109" |

| Utah admitted.

| March 4, 1903

| style="text-align:center" | 386

| style="text-align:center" data-sort-value="29" | 29

| data-sort-value="31-733" |

| Apportionment following the twelfth census (1900)

| November 16, 1907

| style="text-align:center" | 391

| style="text-align:center" data-sort-value="5" | 5

| data-sort-value="34-271" |

| Oklahoma admitted

| January 6, 1912

| style="text-align:center" | 393

| style="text-align:center" data-sort-value="2" | 2

| rowspan="2" data-sort-value="37-014" | , incorporating

| New Mexico admitted

| February 14, 1912

| style="text-align:center" | 394

| style="text-align:center" data-sort-value="1" | 1

| Arizona admitted

| March 4, 1913

| rowspan="4" style="text-align:center" | 435

| style="text-align:center" data-sort-value="41" | 41

| data-sort-value="37-013" | (Apportionment Act of 1911, §§1–2)

| Apportionment following the thirteenth census (1910). Process returned to the Webster method.

| March 4, 1933

| rowspan="3" style="text-align:center" data-sort-value="0" |

| data-sort-value="46-026" | (Reapportionment Act of 1929)

| Apportionment following the fifteenth census (1930). 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" | (Reapportionment Act of 1929)

| Apportionment following the sixteenth census (1940). First to use the Huntington–Hill method.

| January 3, 1953

| data-sort-value="55-761" |

| Apportionment following the seventeenth census (1950)

| January 3, 1959

| style="text-align:center" | 436

| style="text-align:center" data-sort-value="1" | 1

| data-sort-value="72-345" |

| Alaska admitted.

| August 21, 1959

| style="text-align:center" | 437

| style="text-align:center" data-sort-value="1" | 1

| data-sort-value="73-008.8" | , §8

| Hawaii admitted.

| January 3, 1963

| rowspan="7" style="text-align:center" | 435

| style="text-align:center" data-sort-value="-2" | 2

| data-sort-value="73-008" |

| Apportionment following the eighteenth census (1960)

| January 3, 1973

| rowspan="6" style="text-align:center" data-sort-value="0" |

| rowspan="6" data-sort-value="99-1973" |

| Apportionment following the nineteenth census (1970).

| January 3, 1983

| Apportionment following the twentieth census (1980).

| January 3, 1993

| Apportionment following the twenty-first census (1990).

| January 3, 2003

| Apportionment following the twenty-second census (2000).

| January 3, 2013

| Apportionment following the twenty-third census (2010).

| January 3, 2023

| Apportionment following the twenty-fourth census (2020).

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.

;Citations

References

External links

Congressional Apportionment by the U.S. Census Bureau

United States congressional apportionment

Reapportionment

Number of members

Controversy and history

Past apportionments

Changes per census

2010

2020

List of apportionments

See also

Notes

References

Further reading

External links