Reapportionment
Redistricting or reapportionment is the changing of political borders (in many countries, specifically the electoral district/constituency boundaries) in response to periodic census results. This takes place by law or constitution at least every decade in most representative democracy systems to maintain proportional representation.
A controversial approach to redistricting, gerrymandering, is the deliberate manipulation of political borders for short-term electoral advantage, usually of incumbents or a specific political party.
Redistricting in the United States
Reapportionment of the U.S. House of Representatives (the lower house of the U.S. Congress) occurs every year ending in "1", the year after the U.S. Census Bureau performs the decennial census mandated by the U.S. Constitution. In five states (Hawaii, Idaho, Montana, New Jersey and Washington), congressional reapportionment is performed by an independent, bipartisan commission. In the remaining states, the state legislature has primary responsibility for creating a reapportionment plan, subject to approval by the state governor. Various states also have laws or constitutions mandating that municipal governments do this as well.
Each state has its own standards for creating reapportionment plans. In the states where the legislature is in charge of reapportionment, the possibility of gerrymandering often makes the process politically contentious, especially when the two houses of the legislature, or the legislature and the governor, are of different parties. The federal court system is often involved in resolving disputes over reapportionment plans.
