Every ten years, after the census, states redraw their congressional and legislative district maps. This process, called redistricting, determines which communities vote together and who represents them. But when politicians pick their voters instead of voters picking their representatives, it is called gerrymandering.

What Is Gerrymandering?

Gerrymandering is the practice of manipulating district boundaries to favor a particular party, group, or incumbent. The term dates back to 1812, when Massachusetts Governor Elbridge Gerry approved a state senate district shaped like a salamander. A newspaper mocked it as a “Gerry-mander”—a portmanteau that stuck.

At its core, gerrymandering involves concentrating or dispersing voters in ways that create electoral advantages. Two primary tactics define this:

• Packing: Drawing districts where one party wins by overwhelming margins, “packing” their supporters into fewer districts so they win those seats by huge margins but lose everywhere else.
• Cracking: Splitting opposition voters across multiple districts so they never form a majority anywhere, diluting their voting power.

Both strategies manipulate the geometry of districts to produce outcomes that do not reflect actual voter preferences.

A Brief History of Redistricting

The Constitution requires a census every ten years to apportion seats in the House of Representatives among the states. After each census, states must redraw their districts to reflect population changes.

For most of American history, state legislatures controlled redistricting with little oversight. This meant the party in power could draw maps that protected incumbents and maximized their electoral advantage. Reformers pushed for change, and in 1962, the Supreme Court ruled in Baker v. Carr that federal courts could hear redistricting cases. Two years later, the Court required districts to be “as equal in population as practicable,” establishing the “one person, one vote” standard.

Still, partisan manipulation continued. The Voting Rights Act of 1965 prohibited racial gerrymandering, but it did not address partisan gerrymandering. Over time, as mapping technology improved and data on voter behavior became more granular, the potential for sophisticated manipulation grew.

How Districts Are Drawn

Modern redistricting relies on sophisticated software and detailed voter data. Cartographers can now predict with remarkable accuracy how specific households will vote based on past behavior, party registration, and consumer data.

Redistricting principles guide mapmakers, though they vary by state:

• Compactness: Districts should not be contorted or sprawling. Compactness makes districts easier to understand and ensures communities are not bizarrely split.
• Communities of interest: Districts should keep together neighborhoods, towns, or groups that share common concerns—like urban areas, agricultural regions, or college towns.
• Contiguity: All parts of a district must be connected.
• Equal population: Each district must have roughly the same number of people.

These principles exist alongside constitutional requirements, but they often conflict with each other—and with the political incentives to draw favorable maps.

The Debate: Efficiency Gap vs. Partisan Fairness

Gerrymandering most contested question is how to measure it. Two metrics dominate the discussion:

The efficiency gap measures the difference between each party “wasted votes”—votes cast for losing candidates plus excess votes beyond what was needed to win. If one party consistently wastes far more votes than the other, the map may be gerrymandered.

Partisan fairness asks whether the share of seats a party wins reflects its share of the vote. If Democrats win 55% of votes but only 40% of seats, something may be wrong with the map.

Critics of both metrics argue they are imperfect. A party might win more seats simply because its voters are geographically concentrated. Additionally, there is no consensus on what level of disparity constitutes gerrymandering versus natural variation.

The Supreme Court weighed in on partisan gerrymandering in Rucho v. Common Cause (2019), ruling that federal courts have no jurisdiction to hear such claims. The Court found these questions fundamentally political, not justiciable—leaving the issue to Congress and state legislatures.

State-Level Reform Efforts

Since federal courts stepped back, reform has happened primarily at the state level. Several approaches have gained traction:

Independent redistricting commissions: Several states now use commissions—rather than legislatures—to draw district lines. California, Arizona, and Michigan use independent or citizen-led commissions with varied structures. These bodies aim to remove partisan incentives from the process.

Advisory commissions: Some states retain legislative control but add advisory commissions that propose maps for consideration.

Criteria-based rules: States like Iowa use specific criteria to guide map-drawing, such as limiting the number of counties split or requiring that districts follow existing political boundaries when possible.

Mathematical standards: Some reform proposals would set explicit limits on the efficiency gap or require that maps pass certain statistical fairness tests.

The effectiveness of these reforms varies. Independent commissions have reduced some partisan bias, but studies show they do not eliminate it entirely. Map-drawing remains a highly political exercise, even when conducted by well-intentioned citizens.

Impact on Elections and Representation

Gerrymandering affects American politics in several measurable ways:

• Incumbent protection: Sitting representatives win re-election at rates exceeding 90% in many states, partly because districts are drawn to ensure their safety.
• Reduced competition: Many House seats are “safe” for one party, meaning the general election is effectively decided in the primary. This pushes both parties toward extremes.
• Disproportionate representation: The party that controls redistricting often wins more seats than its vote share would suggest.
• Voter disillusionment: When maps seem rigged, voters may check out entirely—contributing to declining participation.

Research from the Brennan Center for Justice found that during the 2022 midterms, only 17% of House races were genuinely competitive—down from over 40% in the 1970s. While many factors contribute to this decline, gerrymandering plays a significant role.

What Voters Can Do

Understanding gerrymandering is the first step toward addressing it. Voters can:

• Research how their state draws districts and who controls the process
• Support ballot initiatives for independent commissions where available
• Pay attention to candidates who prioritize redistricting reform
• Vote in primaries, where many competitive races are decided

While gerrymandering will not be solved overnight, informed citizens are better equipped to demand fair representation. The system only works when voters understand the rules—and insist they are applied equally.

---

Featured image: Photo by Edmond Dantès on Pexels