Congressional districts in the United States are electoral divisions for the purpose of electing members of the United States House of Representatives. The number of voting seats within the House of Representatives is currently set at 435, with each one representing an average of 761,169 people following the 2020 United States census. The number of voting seats has applied since 1913, excluding a temporary increase to 437 after the admissions of Alaska and Hawaii. The total number of state members is capped by the Reapportionment Act of 1929.Public Law 62-5 of 1911, though Congress has the authority to change that number. In addition, each of the five inhabited U.S. territories and the federal district of Washington, D.C., sends a non-voting delegate to the House of Representatives.

The Bureau of the Census conducts a constitutionally mandated decennial census whose figures are used to determine the number of congressional districts to which each state is entitled, in a process called "apportionment". The 2022 elections were the first to be based on the congressional districts which were defined based on the 2020 United States census.

Each state is responsible for the redistricting of districts within their state, while several states have one "at-large" division (Alaska, Delaware, North Dakota, South Dakota, Vermont, and Wyoming). Redistricting must take place if the number of members changes following a re-apportionment, or may take place at any other time if demographics represented in a district have changed substantially. Setting the boundaries of states' congressional districts is the responsibility of state governments, who often gerrymander districts for various reasons. Districts may sometimes retain the same boundaries, while changing their district numbers.

Each congressional district is expected to be equal in population to all other congressional districts in a state. The boundaries and numbers shown for the congressional districts are established by their respective state's constitution or court orders in the apportionment and redistricting cycle.

Delimitation Many other nations assign independent bodies to oversee and mandate the delimitation of boundaries; however, in some nations the legislature manages this process. In the United States, legislatures play a commanding role in the redistricting (as delimitation is referred to in the United States) of congressional districts. The redrawing of boundaries occurs after the decennial census; single-member constituencies are responsible for the election of the legislators that govern this process.Gelman, A., King, G. (1994). Enhancing democracy through legislative redistricting. The American Political Science Review, 88, 541–559. In 25 states the state legislature is responsible for creating the redistricting plan, but six states (Alaska, Delaware, North Dakota, South Dakota, Vermont and Wyoming) do not require redistricting for the House of Representatives and instead elect a single representative for the entire state.Whitaker, L. (2015). Congressional Redistricting and the Voting Rights Act: A Legal Overview [Ebook] (1st ed., pp. 3–12). Congressional Research Service. Each state has its own constitution and laws surrounding the redistricting process, and most of the modern criteria applied federally have come about through rulings by the U.S. Supreme Court."Redistricting and the Supreme Court: The Most Significant Cases", 2020

Prior to 1962, there was limited federal and state government regulation on redistricting, and these were rarely enforced. However, after the Baker v. Carr (1962) decision redistricting became justiciable and courts became an active participant in the redistricting process of congressional districts as the decision allowed voters to challenge redistricting plans. Since Shaw v. Reno (1993) and Abrams v. Johnson (1997), the courts have invalidated numerous congressional redistricting plans upon the basis of traditional districting principles. These decisions have been surrounded in controversy as the Supreme Court has not identified these 'traditional' criteria explicitly, resulting in the major political parties attempting to abuse the lack of legislation and definition to advantage their respective parties.Bowen, D. (2014). Boundaries, redistricting criteria and representation in the U.S. House of Representatives. American Politics Research, 42(5), 856–895. According to the database of redistricting laws in all fifty states and previous court decisions, the de facto principles are: compactness, contiguity, equal population, and preserving county and city boundaries.

Extremes

Population

Average population: 761,169 people based on 2020 U.S. census. It was 708,377 in 2010. State with the most people in the average district: Delaware (989,948). In 2010, Montana: 994,416. State with the fewest people in the average district: Montana (542,113). In 2010, Rhode Island: 527,624. District with the most people: (989,948). In 2010, : 994,416. District with the fewest people: (545,085). In 2010, also : 526,283.

Area District with the greatest area: , same as in 2010. District with the greatest area that comprises less than an entire state: . In 2010: . District with the smallest area: . In 2010: .

Oldest district , same geographical borders since 1789.

Cook Partisan Voting Index District with the highest Cook PVI score for the Democratic Party: District with the highest Cook PVI score for the Republican Party:

List of districts by area and population The following is a complete list of the 435 current congressional districts for the House of Representatives, and 248 obsolete districts, and the six current and one obsolete non-voting delegations. The list includes the 435 voting districts of the 119th United States Congress, effective from 2025 to 2027.Files downloaded from the U.S. Census Bureau's TIGER/Line Shapefiles for congressional districts. Areas derived from the "ALAND" field in the shapefiles, given in square meters.

Rank District Land area(mi2) Land area(km2) Population