Apportionment
The process of dividing the 435 seats in the U.S. House of Representatives among the 50 states based on their population, as determined by the decennial census. It ensures proportional representation in the lower chamber.
Article I, Section 2 requires House seats to be apportioned among the states “according to their respective Numbers,” recalculated after each decennial census. Since 1929, the total size of the House has been fixed by statute at 435 seats, meaning apportionment today is a zero-sum reallocation: if one state’s population grows faster than the national average, it gains a seat only by another state losing one. The formula used, the method of equal proportions, has been the standard since 1941.
Every state is guaranteed at least one seat regardless of population, which is why Wyoming (under 600,000 residents) gets full representation disproportionate to its population compared with a single district in a larger state. After the 2020 census, seven states gained or lost seats, with Texas gaining two and California losing a seat for the first time in its history as a state.
Common misconception: people often confuse apportionment with redistricting and assume they’re the same process. Apportionment (a federal, census-driven calculation of how many seats each state gets) happens first and is largely mechanical; redistricting (drawing the actual boundary lines of those districts within a state) happens second and is where partisan gerrymandering disputes actually occur.