Reapportionment Law and Legal Definition

Reapportionment is the process of redividing the 435 seats of the United States House of Representatives, based upon each state's proportion of the national population. The preceding decennial census is the baseline or determining how many House seats are allotted to each state. The total number of each state's U. S. House seats, combined with its two U.S. Senate seats, constitutes that state's number of electoral votes in presidential elections.

Every ten years, the boundaries of legislative districts are redrawn based upon changes in population. This process is usually referred to as "redistricting" or "reapportionment". It affects election districts for the state Senate and the state House of Representatives, as well as election districts for the federal House of Representatives in the United States Congress.