Reapportionment and Redistricting

Reapportionment and redistricting are the two processes that allocate the 435 seats in the House of Representatives, as well as seats in state legislatures and many city councils. Both processes help to determine the partisan and geographic makeup of such bodies, and whether racial or ethnic minorities will receive fair representation.

Reapportionment is the redistribution of seats to reflect shifts in population as indicated by the national census, which is conducted every ten years. As it applies to Congress, reapportionment gives additional House seats to states that have gained population over the previous decade, and it takes seats away from states that have lost population or have grown more slowly than the national average. The process works similarly in state, county, or city legislative districts, the areas from which state legislators and local council members are elected.

Redistricting means that the district boundaries are redrawn to adjust to the population changes and reallocation of seats. Most U.S. House members represent a specific area within a state, although seven states with sparse populations have only one House member for the entire state. (See House of Representatives, electing.)

Redistricting usually occurs in the two years following reapportionment. governors and state legislators normally control the mapping process, for congressional districts as well as for state election districts. Counties or cities that have home rule—full or limited independence from the state legislature—may be empowered to draw their own district, ward, and precinct boundaries.

No matter which body does the redistricting, the process may not be over when that body finishes its work. Affected persons or groups often file legal challenges to the maps. The courts sometimes order a second round of redistricting in the middle of a decade, and on occasion they even draw new district maps on their own.

Reapportionment and redistricting have been subjects of debate throughout U.S. history because the Constitution did not specify how they should be done. The framers decreed that House seats would be divided among the states on the basis of population, and that House members would be elected by the people. Beyond that, the Constitution gave little guidance on these subjects, leaving Congress, the courts, and state governments to wrestle with them.

In contrast to the House, the Senate never undergoes reapportionment or redistricting. The Constitution gave each state two Senate seats, and senators are always chosen on a statewide basis. Moreover, the two-senator minimum cannot be changed. Article V states “that no State, without its Consent, shall be deprived of its equal Suffrage in the Senate.”

State senators, however, are elected from smaller districts that are apportioned according to population, much like congressional districts. multimember districts, no longer permitted for the U.S. House, are still common in state elections.

After many decades of debate, the Supreme Court settled the basic goal of reapportionment and redistricting with rulings in the 1960s. The current guiding principle is one person, one vote, which requires that each citizen have approximately the same representation. For Congress, this means that the 435 congressional districts should be as close to equal in population as possible.

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