Redistricting and Gerrymandering Explained

Redistricting is drawing new boundaries for election districts, including congressional districts for the U.S. House of Representatives and districts for state legislatures. States redraw lines after the census to reflect population changes.

Gerrymandering is drawing district boundaries to favor a particular group, political party, officeholder, or electoral outcome. It is the umbrella term. Partisan gerrymandering is one specific type: drawing boundaries to favor a political party.

Who Is Involved in Redistricting?

The process depends on state law, so it works differently from state to state.

The Census Bureau

The U.S. Census counts every person living in the country every 10 years. The Census Bureau also provides the population data states use to draw their districts.

State Legislatures

In most states, the state legislature draws congressional district lines and passes them like other bills. In many of those states, the governor can sign or veto the map.

Commissions

Some states give the job to a redistricting commission, a group of people chosen to draw the maps instead of, or alongside, the legislature. States such as Arizona, California, Colorado, and Michigan use independent commissions for congressional maps.

Courts

Courts can review maps that are challenged in lawsuits. If a court finds that a map breaks the law, it can order a new map or choose one itself.

The People

Voters in some states can approve or reject maps or redistricting rules through ballot measures.

States With 1 District

States with only 1 House seat, such as Alaska, Delaware, North Dakota, South Dakota, Vermont, and Wyoming, elect their representative statewide and do not draw congressional districts.

What Rules Must District Maps Follow?

District maps must follow federal law, and many states add their own rules.

Equal Population

Congressional districts within a state must have nearly equal populations, so that each person's vote carries about the same weight.

The Voting Rights Act

Section 2 of the Voting Rights Act of 1965 prevents voting practices that deny or limit voting rights based on race. It has been used to challenge maps that weaken the voting power of minority voters.

The Constitution

The Fourteenth Amendment's Equal Protection Clause limits how states use race in drawing districts. Under Shaw v. Reno, a map can be struck down when race is the main factor without a strong legal reason.

State Rules

Many states also require districts to be connected, reasonably compact, and respectful of city, county, and community boundaries. Some states ban drawing maps to favor a political party.

What Is Gerrymandering?

Packing

Packing is placing as many voters of one group or party as possible into a small number of districts. That group wins those districts by large margins but has less influence elsewhere.

Cracking

Cracking is spreading voters of one group or party across many districts so they are not a majority in any of them.

Types of Gerrymandering

• Partisan gerrymandering: drawing lines to favor one political party.
• Racial gerrymandering: drawing lines mainly by race without a strong legal reason.
• Incumbent protection: drawing lines to protect current officeholders.
• Prison gerrymandering: counting incarcerated people where they are held instead of in their home communities.

Florida's constitution bars maps drawn to favor an incumbent, and New York counts people in state prisons at their last home addresses for state and local districts.

When Is Gerrymandering Illegal?

Since Rucho v. Common Cause (2019), federal courts do not decide partisan gerrymandering claims, so drawing maps for party advantage is not barred by federal law. State constitutions and state courts can bar it, as Florida's Fair Districts rules do. Drawing lines mainly by race without a strong legal reason violates the Equal Protection Clause, and weakening minority voting power can violate Section 2 of the Voting Rights Act.

Texas and California drew their maps for party advantage, which federal law allows. Both maps faced racial challenges in court, and the Supreme Court allowed both to be used in 2026, with the lower court's Texas ruling reversed in April 2026.

How Did Redistricting Shape the 2026 Midterms?

Several states changed their congressional maps between censuses before the 2026 elections:

• Texas: Lawmakers approved a 2025 map intended to add five Republican seats.
• California: Voters approved Proposition 50 in November 2025 in response to Texas, temporarily replacing commission maps with legislative maps intended to add five Democratic seats through 2030.
• North Carolina: Lawmakers approved a new map in October 2025.
• Ohio: The commission approved a replacement map in October 2025 after the previous map’s limited term.
• Florida: The governor signed a new map in May 2026.
• Tennessee: Lawmakers approved and the governor signed a new map in May 2026.
• Utah: A state court approved a replacement map in November 2025.
• Louisiana: The governor signed a replacement map in May 2026 following a Supreme Court decision.
• Alabama: The Supreme Court allowed use of the legislature’s 2023 map for 2026.
• Missouri: Voters rejected the 2025 map through Proposition A on November 3, about 62% to 38%, leaving the 2022 map in place.

Missouri’s Proposition A vote was a veto referendum.

When Does Redistricting Happen?

Most redistricting happens once every 10 years, after the census. The most recent census was in 2020, and states drew new maps in 2021 and 2022. The next census will take place in 2030, and new maps based on it are expected to be used starting with the 2032 elections.

Redistricting between censuses before the 2026 midterms was unusual. Lawsuits and new state actions may continue to change district lines before the next census.