United States congressional apportionment
United States congressional apportionment is the process[1] 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 assigned 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.[2] Every state is constitutionally guaranteed at least one seat in the House and two seats in the Senate, regardless of population.
The number of voting seats in the House of Representatives has been 435 since 1913, 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.[3] The Huntington–Hill method of equal proportions has been used to distribute the seats among the states since the 1940 census reapportionment.[1][4] 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 census.
The size of a state's total congressional delegation (which in addition to representative(s) includes 2 senators for each state) also determines the size of its representation in the U.S. Electoral College, which elects the U.S. president.
Reapportionment[edit]
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.[7]
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.