A Practical Matter
The timing of redistricting is mostly a function of practicality. Courts only required regular rebalancing of political districts beginning in 1962. Before that, states and local jurisdictions redrew districts on their own schedules if at all. The Supreme Court firmly established a voter’s right to “equal” representation in what is called the “One Person One Vote” cases beginning with Gray v. Sanders 372 U.S. 368 (1963) and Reynolds v. Simms, 377 U.S. 533 (1964). It recognized that each voter’s vote should weigh the same no matter what district they live in and periodic redistricting was required to ensure this. The practical part involves the court’s recognition that the best time to do this is just after the decennial census, which gives the best data on the population of districts. Reapportionment of the U.S. congress also follows this same schedule per the U.S. Constitution.
“In substance, we do not regard the Equal Protection Clause as requiring daily, monthly, annual or biennial reapportionment, so long as a State has a reasonably conceived plan for periodic readjustment of legislative representation. While we do not intend to indicate that decennial reapportionment is a constitutional requisite, compliance with such an approach would clearly meet the minimal requirements for maintaining a reasonably current scheme of legislative representation.” Reynolds v. Simms 377 U. S. 533, at 583-584.
A Constitutional Minimum
At the time of the court’s decision, many state legislatures already had rules requiring redistricting/reapportionment every ten years but few actually followed that schedule on a regular basis. The court in its “one person, one vote” decisions made the ten year cycle a constitutional minimum and even suggested that doing so on a more regular basis might be constitutionally suspect in some cases. By the early 1970’s the ten-year redistricting cycle had become a mainstay in American politics. Fast forward to the present, and just about all 50 states have memorialized this schedule in their state constitutions as well as many local governments.
Redistricting of congressional districts in particular fit well into the ten year schedule since states learn if they have lost gained or broke even on congressional representation shortly (one year) after the census is conducted. Thus, any change in the number congressional representatives necessarily require redrawn districts. Most states require redrawn districts before the end of the second year after the census, thus a good portion of most state legislative and congressional lines were redrawn by the end of 2012.
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