Every ten years, the United States goes through one of the most consequential and least understood processes in American democracy: congressional redistricting. This process determines which neighborhoods, cities, and communities are grouped together into congressional districts, and by extension, who represents them in Washington.
What Is Redistricting?
Redistricting is the process of redrawing the boundaries of congressional districts. It happens after each decennial census, when the U.S. Census Bureau counts every person living in the country. Because populations shift over time, some areas grow rapidly while others lose residents, district lines must be adjusted to maintain roughly equal population across all 435 House districts.
The Redistricting Process Step by Step
First, the Census Bureau conducts the census and delivers population counts to the president. Congress then uses a mathematical formula called the method of equal proportions to determine how many House seats each state receives, a process called apportionment. After the 2020 Census, Texas gained two seats while Colorado, Florida, Montana, North Carolina, and Oregon each gained one. California, Illinois, Michigan, New York, Ohio, Pennsylvania, and West Virginia each lost one seat.
Once each state knows how many seats it has, the actual line-drawing begins. Each state with more than one district must create a new map with district boundaries that reflect the updated population data. This is where the process gets complicated, and often contentious.
Who Draws the Maps?
The answer depends entirely on the state. In most states, the state legislature draws congressional maps, which means the party in power has significant influence over the final result. Some states, like California, Arizona, and Michigan, use independent redistricting commissions designed to reduce partisan influence. A few states use advisory commissions that make recommendations to the legislature, while others use hybrid approaches.
What Is Gerrymandering?
Gerrymandering occurs when district boundaries are drawn to benefit a particular political party or group. The term dates back to 1812, when Massachusetts Governor Elbridge Gerry approved a salamander-shaped district designed to favor his party. Today, sophisticated mapping software allows map-drawers to create districts with surgical precision, packing opposition voters into a few districts or spreading them thinly across many to dilute their influence.
How Redistricting Affects You
If you want to know which district you currently live in following the most recent redistricting, use our free district lookup tool. Your district may have changed from where it was before 2022, and knowing your current district is essential for voting in the correct races and contacting the right representative.
How courts review new maps
After a state adopts a new map, voters and groups can challenge it in court. Federal judges check that the districts hold nearly equal population, since the Supreme Court requires congressional districts to be as close to equal as possible. Courts also apply the Voting Rights Act, which bars maps that weaken the voting power of racial or language minorities. A map found to dilute minority votes, or to sort voters mainly by race without strong justification, can be struck down and sent back for a redraw. Several states have run an election on a court-ordered map after their first version was rejected.
How long a congressional map lasts
A map normally stays in place from the election after the census until the next census ten years later. The lines drawn after the 2020 count govern the elections of the 2020s, including 2026, in most states. That is not always the end of it. A court can order a new map mid-decade if it finds the current one illegal, and a legislature can pass a replacement on its own. When the lines move, your district number can change even if your address does not, so it is worth checking your district before each election.
Independent commissions and reform efforts
Where to see your district lines
To see the lines that apply to you, look up your full address rather than your city or ZIP code, since one town can sit in more than one district. Our home page maps any United States address to its current congressional district, and each state page shows all of that state’s districts on a single map. After a redraw takes effect, check again, because your district number can change while your address stays the same. Knowing your district is the first step to knowing who represents you and which races are on your ballot.
Most states still let the legislature draw congressional maps, but a growing number have handed the job to a commission. Arizona, California, Colorado, and Michigan use independent commissions whose members are not sitting politicians, with the goal of reducing partisan control. Other states use commissions appointed by elected officials, which keeps more political influence in the process. Supporters say independent commissions produce fairer, less contorted districts. Critics say no method is fully neutral and that commissions can deadlock. The trend reflects a long effort to reduce partisan control over the once-a-decade redraw.
Last updated June 18, 2026.
