What it actually is

Gerrymandering is the practice of drawing voting district boundaries to give an advantage to a particular political party or group. It changes which voters are grouped together so one side can win more seats than their raw vote totals might suggest.

There are different kinds. Partisan gerrymandering is done mainly to help a political party win. Racial gerrymandering (including vote dilution) targets racial or ethnic groups in ways that can reduce their ability to elect candidates of choice. Courts and laws treat those issues differently.

The word goes back to the early 1800s: it’s named for Governor Elbridge Gerry after an 1812 Massachusetts district that was said to look like a salamander. The practice, however, appears whenever districts are redrawn.

How it works

Redistricting usually happens after the census, when population counts are updated. Mapmakers — often state legislatures, sometimes independent commissions — use census population data, election results, and mapping software to draw lines.

Two common tactics are called packing and cracking. Packing concentrates the opposing party’s voters into a few districts so they win those overwhelmingly. Cracking spreads those voters thinly across many districts so they lose more often.

Legal limits vary. Racial gerrymanders can violate the Constitution and the Voting Rights Act and are reviewed by courts. In 2019 the U.S. Supreme Court ruled that federal courts cannot decide claims of partisan gerrymandering, leaving those disputes to state courts, state law, and the political process.

A real example

A major recent moment was the U.S. Supreme Court decision in 2019 (Rucho v. Common Cause) that said federal courts are not the proper forum to resolve claims that district lines were drawn for partisan advantage. That decision did not end challenges — it shifted many disputes to state courts and to political and legislative reform efforts.

Separately, courts have long struck down district maps that were drawn to dilute the voting power of racial groups under the Constitution and federal law.

Why it matters to you

District lines shape who represents you in Congress and state government, which affects laws and policies that touch everyday life — schools, roads, taxes, health care, and more.

When maps favor one side, elections can become less competitive and some voters may feel their votes matter less. How lines are drawn can change which ideas get a hearing in government.

Common misunderstandings

Not every oddly shaped district is illegal. To overturn a map, challengers must meet the legal standard that applies: for racial gerrymandering, plaintiffs typically must show that race was the dominant factor in drawing lines; for vote-dilution claims under the Voting Rights Act, challengers usually show a discriminatory effect. The exact tests depend on the law and the court.

Partisan and racial gerrymandering are treated differently in law. Both parties have used aggressive map-drawing at times, and solutions range from court rulings to independent commissions and new state laws.