Usually, every ten years, states redraw the boundaries of their congressional and state legislative districts after new population data becomes available from the Census. Although this process happens nationwide, states do not all redraw district lines in the same way. State laws determine who has the authority to create district maps and how those maps are approved.
In many states, the state legislature has the primary authority to draw district lines. In these states, lawmakers propose and pass district maps as regular legislation. The plans must usually pass both chambers of the legislature and may be signed or vetoed by the governor.
Some states assign the responsibility for drawing district maps to a separate group called a commission. These groups may include citizens, political appointees, or a combination of members. Commissioners review population data and apply districting rules before approving final maps.
Other states divide responsibility between multiple groups. In these cases, one body may develop district proposals while another group reviews or approves them. Some states also create backup procedures in case the primary decision-makers cannot agree on a plan.
Although the process varies across states, redistricting plans must still comply with federal constitutional rules. Congressional districts must contain nearly equal populations, and federal law still prohibits intentional racial discrimination in voting. But a recent Supreme Court decision narrowed how the Voting Rights Act applies to districting, making it harder to require or justify race-conscious district maps.
The examples below show how several states organize their redistricting process.
California
In California, district boundaries for Congress and the state legislature are drawn by the California Citizens Redistricting Commission. This independent body reviews census population data and develops district maps that reflect population changes across the state.
Members of the commission are selected through a screening process rather than elected to office. After reviewing the data and districting requirements, the commission approves final maps. Once the maps are completed, they are delivered to state officials so election administrators can update precinct boundaries and assign voters to the appropriate districts.
Texas
In Texas, the state legislature is responsible for drawing congressional and state legislative district maps. Lawmakers pass redistricting plans through the same legislative process used for other state laws, and the governor may approve or veto the plans.
If the legislature does not complete redistricting for the state legislature, responsibility shifts to a backup group called the Legislative Redistricting Board. This board includes several statewide elected officials.
Once the maps are approved, they take effect in future elections.
New York
In New York, a redistricting commission first develops proposed district maps for congressional and state legislative districts. The commission reviews census data and prepares draft maps for consideration.
The commission then submits its proposals to the state legislature. Lawmakers review the plans and may approve them or make changes in accordance with state rules.
If the commission cannot reach an agreement or the legislature rejects the proposals, the legislature may ultimately pass district maps itself.
Alabama
In Alabama, the state legislature draws congressional and state legislative district boundaries. Lawmakers pass the district maps as regular legislation, and the governor signs the plans into law.
The new district boundaries are then used in future elections.
District maps in Alabama, as in other states, may be reviewed in court if they are challenged under federal law.
Montana
In Montana, district boundaries are drawn by an independent redistricting commission. The commission reviews census population data and develops maps for congressional and state legislative districts.
After the 2020 census, Montana gained a second congressional seat, requiring the creation of two congressional districts for the first time in decades.
The commission develops draft maps, considers public and legislative feedback, and then approves the final district boundaries.