Reapportionment and Redistricting

Reapportionment and redistricting are related terms that pertain to the distribution of the 435 seats in Congress and other legislative bodies, including state legislatures, county boards and city councils, and the demographic and political landscape of each district. Both processes help to determine the partisan and geographic makeup of such bodies, and whether racial or ethnic minorities will receive fair representation. The terms are not synonymous, however.

Reapportionment is the redistribution of the numbers of seats allocated to individual units of government to reflect shifts in population as indicated by the national census, which is conducted every ten years in the spring of the year ending in “0.” And reapportionment has its most universal—and politically important—impact on Congress: States that have had population gains over the previous decade that significantly exceed the average for the nation as a whole can gain one or more seats in the House, at the expense of states that have either lost population and or have grown significantly more slowly than the national average.

There are state legislatures and county or city legislative districts in which reapportionment pertains, almost always in cases in which there are multimember districts. In these circumstances, the number of members assigned to individual districts is affected by population trends over the previous decade. Most states and localities have single-member districts, however, and reapportionment is not a factor in these places.

Redistricting, though, takes place at almost every level of government as districts within states and localities adjust lines to ensure nearly equal population as required by the one person, one vote Supreme Court rulings of the 1960s.

The necessity of redrawing the lines to balance the numbers of residents also gives politicians in most places the opportunity to shape the partisan voter preference of each district, a tactic that dates to the nation's beginnings—the term “gerrymandering” to describe political redistricting was coined in the early 1800s—and has been enhanced in very recent times by computer technology that enables very detailed analyses of local demographics and voting behavior.

Most U.S. House members represent a specific district within a state, although seven states with sparse populations—Alaska, Delaware, Montana, North Dakota, South Dakota, Vermont, and Wyoming—have only one House member apiece. Each of those states is, in effect, a single at-large congressional district. (See house of representatives, electing.)

Redistricting usually occurs in the two years following reapportionment, although there are exceptions. Maine, which has long had just two districts that require only modest changes to bring their populations into balance, defers its redistricting until the third year of the redistricting cycle.

governors and state legislators normally control the mapping process, for congressional districts as well as for state election districts. A handful of states have turned the redistricting process over to government agencies or panels that either are nonpartisan or have memberships [Page 518]relatively balanced between the two major parties. In addition, in almost every decade some states have called upon the state and federal judicial systems to assume responsibility for redistricting when elected officials have failed to agree on and implement a plan on their own.

...