What is gerrymandering?

Gerrymandering is the practice of drawing electoral district boundaries to give one political party an unfair advantage over another. The term comes from a salamander-shaped district drawn in Massachusetts in 1812 under Governor Elbridge Gerry, which a newspaper at the time named a Gerry-mander. Gerrymandering has been a feature of American politics for more than two centuries and continues to shape congressional and state legislative elections today.

Two main techniques are used to gerrymander districts. Packing concentrates supporters of the opposing party into a small number of districts where they win by huge margins, leaving them with fewer total seats than their share of the statewide vote would suggest. Cracking spreads supporters of the opposing party across many districts so they form a minority in each, denying them the chance to win. A skillful gerrymander uses both techniques together to maximize the favored party's seats relative to its share of the vote.

Modern computer-assisted redistricting allows mapmakers to draw districts with extraordinary precision, using detailed voting data to predict how each precinct or even each block will vote. This has made partisan gerrymandering more effective and more controversial in recent decades. North Carolina and Maryland have been particular focal points, with Republican-controlled North Carolina drawing aggressive maps favoring Republicans and Democratic-controlled Maryland drawing aggressive maps favoring Democrats.

The Supreme Court has issued mixed rulings on gerrymandering. Racial gerrymandering, which uses race as the predominant factor in drawing district lines, is generally unconstitutional under the 14th Amendment unless narrowly tailored to comply with the Voting Rights Act. Partisan gerrymandering, where political party affiliation rather than race is the dominant factor, was held to be a non-justiciable political question in Rucho v. Common Cause (2019), meaning federal courts cannot strike down maps for being too partisan. State courts can still strike down maps under state constitutions.

Several state supreme courts, including in Pennsylvania (2018) and North Carolina (2022), have struck down gerrymandered maps. Reform efforts include independent redistricting commissions, which exist in California, Arizona, Michigan, Colorado, and other states; nonpartisan staff drawing maps in Iowa; and proposed federal legislation that has not yet passed.

Critics argue gerrymandering distorts democracy by allowing politicians to choose their voters rather than the other way around. Defenders argue redistricting is a political process and that any redrawing of lines reflects political choices.