How House seats moved between the states, 1910 to 2020

The US House of Representatives has had 435 seats since 1913, and after every census they are shared out again in proportion to each state's population. Over a century that quiet arithmetic has moved more political weight than almost any election. In 1910 the Northeast and the Midwest held 266 seats and the South and the West 167. After the 2020 census the figures were 167 and 268, almost exactly the reverse.

This page follows that shift census by census and state by state. Every number comes from the apportionment file the Census Bureau publishes for the censuses of 1910 to 2020, and the tables below are computed from it.

The century in four numbers

• +41seats for California, from 11 in 1910 to 52 today, the largest gain of any state
• -19seats for Pennsylvania, from 36 to 17, the largest loss
• 27seats changed states after the 1930 census, the biggest reshuffle, because the 1920 census never produced one
• 104seats in the West, against 31 in 1910 (33 once Arizona and New Mexico joined in 1912)

How the seats are shared out

The Constitution orders a count of the population every ten years and gives every state at least one representative. The Apportionment Act of 1911 set the House at 433 members, with one more seat each for Arizona and New Mexico on their admission in 1912, which brought the total to 435.

The 1920 census is the only one in American history that was never followed by a reapportionment. It was the first to find more Americans living in urban areas than in rural ones, rural members of Congress resisted the shift, and the 1910 allocation stayed in force for twenty years. The Reapportionment Act of 1929 ended the stalemate: it fixed the House at 435 and made the process automatic after each census. That is why this page skips from 1910 to 1930.

Since the 1940 census the seats have been divided by the method of equal proportions, written into law in 1941. The House grew to 437 for a few years after Alaska and Hawaii joined in 1959, and went back to 435 with the apportionment of the 1960 census. New seat counts take effect at the House elections two years after the census, so the 2020 count governs the elections of 2022 to 2030 and sets each state's electoral votes for the 2024 and 2028 presidential elections.

North against South and West

South + WestNortheast + Midwest

Seats by Census region after each census

The Northeast lost seats at every census from 1930 on, falling from 123 to 76, and the Midwest did the same, from 143 to 91. The South held between 133 and 136 seats for half a century, then gained at every census from 1970, reaching 164. The West gained at every census, from 31 seats to 104, and has had more seats than the Northeast since 1990. Its share of the country's population rose from 7.7% to 23.8%.

The biggest winners

California had 11 seats in 1910 and has 52 today. It gained at every census from 1930 to 2000, including nine seats in 1930 alone, held 53 after 2000 and 2010, and lost one in 2020, the first loss in its history as a state. Its population went from 2.4 million to 39.5 million.

Florida is the steadiest climber of all: it gained seats at ten censuses in a row, every one from 1930 to 2020, going from 4 to 28. Its population was 752,619 in 1910 and 21,538,187 in 2020, 28.6 times as many.

Texas went from 18 seats to 38, with a gain at every census since 1950, eight in a row, including four seats after 2010. Arizona entered the Union in 1912 with one seat and has nine. Further down the list, Washington doubled from 5 to 10, Colorado from 4 to 8, and Nevada went from 1 to 4.

The biggest losers

Pennsylvania lost seats at ten censuses in a row, every one from 1930 to 2020, falling from 36 to 17. No state has lost more.

New York peaked at 45 seats after the 1930 and 1940 censuses, a delegation no state matched until California reached 52 in 1990. It has lost seats at eight censuses in a row since 1950, including five at once after 1980, the largest single loss of the century, and has 26.

The Midwest shrank across the board. Illinois went from 27 seats to 17, Missouri from 16 to 8 and Iowa from 11 to 4. Ohio held 24 seats from 1930 to 1960 and has 15 after six losses in a row. Michigan rose from 13 to 19 with the car industry, peaking in 1960 and 1970, and is back at 13 after five losses in a row. West Virginia went from 6 seats to 2, and was one of three states, with Illinois and Mississippi, whose population fell between 2010 and 2020.

The states that never moved

Delaware and Wyoming have had one seat after every census in the period, and Idaho and New Hampshire two. Alaska (one seat) and Hawaii (two) have not changed since their first apportionment in 1960. Montana came close: two seats until the 1990 census took one away, then its second seat back in 2020.

Every state, 1910 to 2020

Seats after selected censuses, the change since the state's first apportionment in the period, and its peak. Arizona and New Mexico start from their admission in 1912, Alaska and Hawaii from 1960.

How many seats moved at each census

1960 includes the three seats Alaska and Hawaii received on their first apportionment.

Where Americans moved: population 1910 and 2020

The seats follow the people. These are the six fastest and the six slowest growing states over the 110 years.

Fastest growing

Slowest growing

How many people one seat represents

In 1910 the House had one member for roughly every 212,000 residents. After the 2020 census the Census Bureau's average was 761,169 people per seat. Because seats come whole, the gap between states is wide: Montana's two seats average 542,704 people each, the fewest, while Delaware's single seat covers 990,837, the most.

The full table: seats after every census

1920 is left out because no reapportionment followed it.

Source and method

All figures come from the Census Bureau's historical apportionment file (apportionment.csv), which gives the resident population and the number of representatives of every state at each census from 1910 to 2020. Regions are the four Census Bureau regions. Seat counts are the ones apportioned at each census, not the number of members sitting on a given day. The page is rebuilt from that file by a script, and each figure quoted in the text is checked against it.

Frequently asked questions

Which state has gained the most House seats since 1910?

California, from 11 seats in 1910 to 52 after the 2020 census, a gain of 41. Florida grew the most in proportion, from 4 seats to 28.

Which state has lost the most House seats?

Pennsylvania, from 36 seats in 1910 to 17 after the 2020 census, a loss of 19. New York lost 17 over the same period, from 43 to 26, after a peak of 45.

Why were House seats not reapportioned after the 1920 census?

Congress never passed a reapportionment law for the 1920 census, the first to show more Americans in urban areas than rural ones. The 1910 allocation stayed in force until the Reapportionment Act of 1929 made the process automatic from the 1930 census on.

Why does the House have 435 members?

The Apportionment Act of 1911 set 433 seats plus one each for Arizona and New Mexico on admission, making 435, and the Reapportionment Act of 1929 fixed that number. The House briefly had 437 members after Alaska and Hawaii joined in 1959, until the 1960 census apportionment.

Which states have never gained or lost a seat since 1910?

Delaware and Wyoming, with one seat each, and Idaho and New Hampshire, with two. Alaska and Hawaii have not changed since their first apportionment in 1960.

When will House seats change next?

After the 2030 census. The Census Bureau must deliver the state counts within nine months of census day, and the new seat numbers apply from the 2032 elections, including that year's presidential election.

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