reapportionment

1. The act of reapportioning or the state of being reapportioned.
2. Redistribution of representation in a legislative body, especially the periodic reallotment of U.S. congressional seats according to changes in the census figures as required by the Constitution.

Every ten years the United States conducts a census of its population, after which the House of Representatives is reapportioned—that is, the seats are reallocated in proportion to the states' populations. Some states gain congressional districts, some lose districts, and some keep the same number.

By statute, Congress sets the total number of representatives in the House. At first, the House simply enlarged its membership to accommodate new states and a growing population. After the 1790 census the House expanded from 65 to 105 members. The numbers increased steadily until 1911, when House membership reached 435. Since then, that number has remained the ceiling. After each census the states redraw the lines of their congressional districts to conform to any changes in the population. (In addition to the 435 voting members, the House of Representatives also has various delegates who represent U.S. territories.)

In the 1790s each member of the House represented about 33,000 people. By the 1990s each member represented nearly 600,000 people. However, at times the population size of congressional districts has varied widely. For many years the state legislatures that drew the boundaries for their state's congressional districts favored less-populated rural areas over cities by giving the rural areas greater proportional representation. In the 1964 case of Wesberry v. Sanders, the Supreme Court ruled such inequalities unconstitutional. The Court ordered that congressional districts be drawn to provide “one person, one vote.”

The majority party in the state legislature invariably tries to draw the reapportionment lines to favor its own candidates in elections. Sometimes they resort to gerrymandering—drawing oddly shaped districts to combine areas where their party registration is the strongest. The Voting Rights Act of 1982 encouraged states not to divide up districts in such a way that minority groups cannot elect their own candidates.

In the redistricting that followed the 1990 census, this led to the creation of many more districts where African-American and Hispanic-American candidates stood a better chance of election. But the Supreme Court restrained this trend by ruling in Miller v. Johnson (1995) that states could not use race as the predominant reason for drawing a district's boundaries.

See also Gerrymandering

The changing of the boundaries of a legislative district or number of legislative representatives to which a district is entitled in order to reflect the population of the district. The object of reapportionment is to give effect to the one person, one vote principle. Under Article I, Section 2 of the Constitution, the U.S. House of Representatives is to be chosen "by the people of the several States." Under this provision, reapportionment of congressional districts is required every ten years in order to make "as nearly as practicable, one [person's] vote in a congressional election . . . Worth as much as another's." 376 U.S. 1. Under the equal protection clause of the Constitution, the seats in a state legislature must also be apportioned on a population basis. 369 U.S. 186. Compare gerrymander. The term reapportionment also applies to the revaluation of real estate for local taxes.

The noun has one meaning:

Meaning #1: a new apportionment (especially a reallotment of congressional seats in the United States on the basis of census results)
  Synonyms: reallotment, reallocation