Introduction: By Legislatures, Governors, Commissions and Courts | 1991 to Date
When most analysts look at redistricting, they see complexity. The Constitution delegates to the state legislatures the power to draw the boundaries of congressional districts. The Supreme Court has established limits on the states, such as “one person, one vote” and restraints on using racial considerations to be the predominant concern when redistricting. Congress has restricted states’ powers through the Voting Rights Act. Many state constitutions also require redistricting to abide by so-called “traditional redistricting principles,” such as compactness and contiguity. For more, see NCSL’s Redistricting Criteria webpage.
Some states delegate redistricting responsibilities to commissions, although most charge their legislatures with the task. Regardless of the criteria used in a state or who draws the maps, political realities color the redistricting process and often lead to court challenges.
NCSL has provided charts that tell the redistricting story for each state in each of the past three redistricting cycles for all the states. See the three links below.
Additionally, Redistricting Plan Success Rates 1970s-2010s provides the rate of success in creating redistricting plans, whether the plan was drawn by the legislature or a commission. In this table, “success” means that a plan was either not challenged in court or, if challenged, was upheld without change.
NCSL thanks Peter Wattson for his invaluable work in gathering the data provided here.
The three charts above read left-to-right in each state, with a section for each of three maps: the state’s Senate map, the state’s House map, and the state’s congressional map for the 46 states that have more than one member of the U.S. House of Representatives. Each section is a chronology of the entire redistricting process over several years. A forward slash (/) means a plan was rejected in some way (either by a veto or by the courts), and some part of the redistricting process was repeated. For example, Nevada in 2011-2020 saw its Legislature draw maps (D) that were vetoed by the governor (V). The Legislature didn’t attempt to override the governor’s veto, leaving the state without a plan. Ultimately, the state’s courts drew the plan (D), which is in place today.
A—Approved plan drawn by another; C—Corrected plan; D—Drew plan; N—No plan needed; P—Pending decision; R—Rejected plan; V—Vetoed plan; VO—Veto overridden