Apportionment

Apportionment is the process of dividing the seats in the U.S. House of Representatives among the states after each decennial census. Article I of the Constitution requires representatives to be apportioned by population, and the House size has been fixed at 435 members by statute since 1929, with a short interlude for new states.

Since 1941, the Census Bureau has used the "method of equal proportions" to allocate seats: each state gets one, and the remaining are assigned using a priority formula based on population. States that grow slowly can lose seats and those that grow quickly gain them. The results also change the state's votes in the Electoral College, since electors equal House seats plus two. States then draw new lines in redistricting.

Controversies include who is counted. The Fourteenth Amendment says the whole number of persons in each state is counted, which includes noncitizens and unauthorized immigrants; critics, including some conservatives, have sought to exclude them, an effort that courts have not accepted, and debates around noncitizen voting sometimes touch on it. There are also disputes over census accuracy, undercounts and the cap on House size, which some want enlarged.