Redistricting & Electoral Geography

The process of redrawing the boundaries of electoral districts, typically conducted after each decennial census to account for population shifts. Redistricting determines which communities are grouped together into the same congressional, state legislative, or local districts, and therefore which voters each elected official represents. Because district lines have enormous consequences for electoral outcomes, redistricting is one of the most politically consequential processes in American democracy and is often fiercely contested.

The manipulation of electoral district boundaries to give one political party, racial group, or other interest an unfair advantage in elections. The term dates to 1812, when Massachusetts Governor Elbridge Gerry signed a law creating a strangely shaped district that critics said resembled a salamander, producing the portmanteau "gerrymander." Gerrymandered maps can entrench political power for decades by packing opposition voters into as few districts as possible or spreading them too thin to form majorities anywhere. It remains one of the most significant structural challenges to fair representation in the United States.

A form of gerrymandering in which district lines are drawn to maximize the electoral advantage of one political party at the expense of the other. Partisan gerrymandering typically involves two main strategies: packing, which concentrates opposition voters into a small number of districts where they win by large margins, and cracking, which splits opposition voters across multiple districts so they cannot form a majority in any of them. In 2019, the Supreme Court ruled in Rucho v. Common Cause that federal courts cannot review partisan gerrymandering claims, leaving the issue to state courts and legislatures.

The drawing of district lines in a way that dilutes the voting power of a racial or ethnic minority group or, in some cases, packs minority voters into districts in a way that limits their broader influence. Racial gerrymandering that diminishes minority voting power can violate the Voting Rights Act and the Equal Protection Clause of the 14th Amendment and has been the subject of significant litigation. Courts have struck down racially gerrymandered maps in multiple states, though the legal standards for what constitutes an illegal racial gerrymander continue to evolve.

A defined geographic area within which eligible residents vote for the same set of candidates or ballot measures. Voting districts exist at multiple levels: congressional districts determine U.S. House races, state legislative districts determine state house and senate races, and local districts determine city council, school board, and other local races. The boundaries of voting districts are redrawn periodically through the redistricting process to reflect population changes.

One of 435 geographic areas into which the United States is divided for the purpose of electing members of the U.S. House of Representatives. Each congressional district elects one representative, and districts are apportioned among states based on population as measured by the decennial census. States with growing populations may gain congressional districts while states with shrinking or slower-growing populations may lose them. Within each state, the boundaries of congressional districts are drawn by the state legislature or an independent redistricting commission.

The smallest unit of election administration, a defined geographic area within which all voters cast their ballots at the same polling place and whose votes are counted and reported together. Precincts are used for managing voter rolls, assigning voters to polling locations, and reporting election results. Precinct-level results are the most granular election data publicly available and are frequently used by campaigns, researchers, and journalists to analyze voting patterns.

A subdivision of a city or town used for administrative and electoral purposes. In cities that use ward-based elections, each ward elects its own representative to the city council or other governing body. Ward boundaries, like other district boundaries, are redrawn periodically to reflect population changes. In some cities the terms ward and district are used interchangeably, while in others they have distinct meanings.

An election in which candidates are chosen by voters across an entire jurisdiction, such as a city or county, rather than by voters in specific districts or wards. In an at-large system, every voter votes on every seat up for election. Supporters argue at-large elections encourage candidates to represent the whole community rather than just their district. Critics argue they can dilute the voting power of minority communities that might be able to elect a representative of their choice from a geographically concentrated district but cannot do so when competing citywide.

An electoral district in which a racial or ethnic minority group makes up a majority of the voting-age population. Majority-minority districts are sometimes drawn intentionally to provide minority communities with a meaningful opportunity to elect a representative of their choice, a goal supported by the Voting Rights Act. The creation of majority-minority districts has been a subject of significant legal and political debate, including questions about when drawing such districts is required, permitted, or itself a form of racial gerrymandering.

A body established to draw electoral district boundaries that is independent from the state legislature, designed to reduce partisan manipulation of the redistricting process. The composition, authority, and independence of redistricting commissions vary significantly by state. Some commissions are truly independent, with members selected through a process designed to exclude partisan officeholders and party insiders. Others are advisory, with the legislature retaining final approval. Research suggests that independent commissions tend to produce more competitive and representative district maps than legislatures drawing their own districts.

The official count of the population of the United States conducted by the federal government every ten years, as required by the Constitution. The census collects data on where people live, their age, race, and other demographic characteristics. Census data is used to apportion seats in the U.S. House of Representatives among the states, to draw congressional and state legislative district boundaries, and to distribute federal funding. An accurate census is essential to fair representation, which is why efforts to discourage participation or add questions that might suppress responses are closely watched and frequently contested.

The process of distributing the 435 seats in the U.S. House of Representatives among the fifty states based on population as measured by the decennial census. States with larger populations receive more seats and therefore more congressional representation, while states with smaller populations receive fewer. Every state is guaranteed at least one representative regardless of population. Following each census, some states gain seats while others lose them, which can significantly affect the balance of power in Congress and in the Electoral College.