Case

What Is Gerrymandering, and Why Does It Keep Happening?

Gerrymandering is drawing election districts so that one side wins more seats than its votes alone would earn. It works because, in most states, the people drawing the lines are the politicians who will run inside them. Here is how it works, why courts rarely stop it, and one way to end it.

Updated September 13, 2026 · 4 min read · An independent project; the site’s own view is marked where it appears.

The short answer

Every ten years, after the census, each state redraws the districts its members of the U.S. House are elected from. Gerrymandering is drawing those districts so that one party wins more seats than its share of the vote would otherwise give it, or so that particular incumbents cannot lose. The word comes from Elbridge Gerry, the Massachusetts governor who in 1812 signed off on a district shaped like a salamander.

The technique has two moves. Packing crams the other side's voters into a few districts they win by enormous margins, so their surplus votes are wasted. Cracking spreads the rest thinly across districts they narrowly lose. Same voters, same votes, different result.

Map A: the same voters, spread evenly

Purple wins 5 seats to 0 with 60% of the vote.

Purple 6–4

Map B: Purple packed into two districts, cracked elsewhere

Gold wins 3 seats to 2 with 40% of the vote.

Purple 10–0

Gold 3–7

Gold 4–6

Fifty voters, thirty Purple and twenty Gold. In Map A, Purple wins every seat. In Map B, twenty Purple voters are packed into two districts and the rest are cracked across three, and Gold wins a majority of the seats with forty percent of the vote. Real districts hold about 760,000 people, and mapmakers have block-level data on how every neighborhood votes, so the effect can be engineered with precision.

Who draws the lines

In most states, the legislature draws the congressional map and the governor signs it, like any other bill. The Constitution leaves the "manner" of House elections to state legislatures unless Congress overrides them, and Congress has required only that each district elect one member.¹ A handful of states have handed the pen to commissions of varying independence. Iowa has its nonpartisan legislative staff draw maps under fixed rules, with no election results, party data, or incumbents' addresses allowed as inputs, and the legislature then votes the map up or down.²

That is the whole problem in one sentence: in most of the country, the people with the most to gain from a map are the ones who draw it. Both parties do it where they can, and each points to the other side's maps as the reason.

Why courts rarely stop it

Federal courts do strike down maps that dilute minority voting strength or sort voters by race without justification; those cases are common and often succeed. But in 2019 the Supreme Court held, 5 to 4, that claims a map is too partisan "present political questions beyond the reach of the federal courts."⁴ Nothing in federal law forbids redrawing a map in the middle of a decade, either; when Texas did that in 2003, the Court let most of the map stand.³

So whether a partisan map can be challenged depends on the state. Some state constitutions or voter-passed laws forbid it, and some state courts enforce them: in November 2025 a Utah court threw out the legislature's map because it "was drawn with the purpose to favor Republicans," in violation of a law Utah voters had passed, and put a different map in its place.¹⁰ Most states have no such rule.

Why it is in the news

The 2025–26 redraws · as of September 13, 2026

Maps are usually redrawn once a decade. In 2025, at the president's urging, Texas redrew its map mid-decade for an estimated gain of up to five Republican seats.⁵ California's voters answered in November, approving a legislative map estimated to be worth about five Democratic seats and setting their independent commission aside through 2030.⁶ ⁷ North Carolina, Florida, Tennessee, and Louisiana followed with new Republican maps;⁸ ¹² ¹⁴ ¹³ Ohio's bipartisan commission drew a new map because a state rule limited the old one to two elections;⁹ a Utah court imposed one.¹⁰ Three efforts failed: Indiana's Republican senators voted their map down, Missouri's was suspended by a citizen referendum petition, and Virginia's courts struck the amendment behind a Democratic redraw.¹¹ ¹⁶ ¹⁵

By the Cook Political Report's measure, the number of House districts with a presidential lean within five points of even fell from 87 to 77, and the median district moved two points toward Republicans.¹⁷ Seat effects are analysts' estimates, not results.

Why it matters beyond the seat count: in a safely drawn district the real contest is the party primary, where turnout is low and the most committed voters decide. The general election that most people vote in becomes a formality. That is true whichever party drew the lines.

What could change

Three kinds of fixes are on the table. Rules for the mapmakers, like bans on using partisan data, which work only where a court will enforce them. Commissions, which change who holds the pen but leave someone holding it, and which a legislature or a referendum can undo, as California's voters did to their own commission's map. And taking the pen away entirely, which is the direction this site argues for.

Where Common Sense Again comes in

A public formula draws the districts, not the politicians

Voters should choose their politicians, not the other way around. The common-sense fix is not to hand the pen to a better group of people; it is to take the pen away from everyone, so that no one in either party gets to pick who votes for them.

This site proposes that congressional districts be generated by a published formula from Census counts alone, under fixed rules in a fixed order: equal population, contiguity, the fewest counties split, then the fewest cities, then the most compact shape, then set tie-breakers. The formula never sees election results, party registration, or where incumbents live, except where federal voting-rights law expressly requires it. The code and the inputs are public, and the same code runs in every state, which removes the argument that one state must redraw because another did. Iowa's process is the nearest existing example; the formula takes it further by removing the staff's judgment and the legislature's vote.²

What it promises is narrow: that no one chose the lines. It does not promise proportional or competitive results. Compact districts still tilt toward the party whose voters are spread out rather than packed into cities,¹⁸ and someone still has to write the rules and the code, which is why the proposal fixes them in statute and makes every deviation reviewable in court. Those limits are part of the proposal, not objections to it.

Read the repair and its evidence →

Go further

Gerrymandering is one of three rules this site argues produce the same result: politicians who answer to the most committed slice of their own party rather than to most voters. The three-minute case lays out that pattern, the other two rules, and what would change them.

Read the three-minute case →

The repair in full → the formula, the voting-rights exception, and the open questions.
The scorecard → how the site will know whether any of this is working.
Objections, answered → including the case that a blind formula just hides the bias in the geography.

Share this caseEmail Post on X

Sources

Primary records first. Where a source has a known lean or a limit, the note says so. Records marked with an S-number also appear in the site’s source register.

1.PRIMARYU.S. Constitution, art. I, sec. 4, cl. 1 (the Elections Clause); 2 U.S.C. § 2c, requiring single-member districts in states with more than one representative. law.cornell.edu →
2.PRIMARYIowa Code chapter 42: § 42.4 sets the standards (congressional districts within one percent of ideal population; the fewest counties and cities divided; contiguity; compactness; no drawing to favor a party or incumbent or to dilute minority voting strength; and no use of incumbents' addresses, political affiliations, previous election results, or demographic information other than population counts, except as required by the Constitution and federal law); § 42.3 assigns the drawing to the nonpartisan Legislative Services Agency, and §§ 42.5–42.6 provide for the General Assembly's vote on each plan. The current process dates from 1980. legis.iowa.gov → S37
3.PRIMARYLeague of United Latin American Citizens v. Perry, 548 U.S. 399 (2006). The Court rejected the statewide challenge to Texas's 2003 mid-decade map and upheld most of it, while finding one district violated Section 2 of the Voting Rights Act. Justice Kennedy's opinion, in a part no other Justice joined, observed that for a mid-decade redistricting "the Constitution and Congress state no explicit prohibition." law.cornell.edu →
4.PRIMARYRucho v. Common Cause, 588 U.S. 684 (2019), 5–4: partisan gerrymandering claims "present political questions beyond the reach of the federal courts." The holding concerns federal courts; the opinion itself notes that state constitutions and state courts, state statutes, and Congress remain able to address partisan gerrymandering. law.cornell.edu →
5.REPORTINGThe Texas Tribune, “Texas' new congressional map can be used, Supreme Court rules,” April 27, 2026: the map was enacted in summer 2025 to add as many as five Republican seats; federal judges found substantial evidence of racial gerrymandering in November 2025; the Supreme Court stayed that ruling in December and reversed it April 27, 2026, with three Justices dissenting. texastribune.org →
6.PRIMARYCalifornia Secretary of State, Statement of Vote, November 4, 2025 Special Election, certified results: Proposition 50, 7,453,339 yes (64.4%), 4,116,998 no (35.6%). The measure's effect, per the official voter information guide, is to replace the Citizens Redistricting Commission's congressional map with a legislative map for the elections through 2030. elections.cdn.sos.ca.gov →
7.REPORTINGNPR, “California voters allow Democrats to redraw congressional map,” November 4, 2025: the Proposition 50 map could net Democrats as many as five House seats in 2026. npr.org →
An analysts' estimate reported at the time of the vote, not a result.
8.REPORTINGNPR, “North Carolina Republicans approve a new congressional map,” October 21–22, 2025 (House vote 66–48); a federal three-judge court later declined to block the map for 2026. npr.org →
9.REPORTINGOhio Capital Journal, “Ohio Redistricting Commission unanimously passes congressional map furthering GOP advantage,” October 31, 2025. Under Ohio Constitution article XIX, a congressional plan adopted without the required bipartisan support is effective for only two general elections, which is why the 2021 map had to be replaced before 2026. ohiocapitaljournal.com →
10.PRIMARYLeague of Women Voters of Utah v. Utah State Legislature, Third Judicial District Court, Salt Lake County, ruling and order of November 10, 2025: the court found the legislature's Map C "was drawn with the purpose to favor Republicans" in violation of Proposition 4's prohibition on partisan gerrymandering and adopted the plaintiffs' Map 1 as the remedial congressional map. redistricting.lls.edu →
A state trial court applying a state statute, cited as an example that some state law does reach partisan map-drawing.
11.REPORTINGIndiana Capital Chronicle, “Senate Republicans reject Trump's plea for gerrymandered maps,” December 11, 2025: the Senate voted 31–19 against House Bill 1032, with 21 Republicans joining all 10 Democrats. indianacapitalchronicle.com →
12.REPORTINGWUSF, “Florida Supreme Court rejects a challenge to a new redistricting map,” June 11, 2026: the map signed May 4, 2026, designed to gain up to four Republican seats, stays in place for 2026 after a 6–1 ruling denying an injunction without reaching the merits; the lawsuit continues. wusf.org →
13.REPORTINGUPI, “Louisiana legislature approves new congressional map,” May 29, 2026: the new map has one majority-Black district instead of two. upi.com →
14.REPORTINGThe Hill, “Federal judges allow Tennessee congressional map dividing majority-Black Memphis district,” July 24, 2026: the legislature approved the map May 7, 2026; a three-judge federal panel declined to enjoin it for the 2026 elections. thehill.com →
15.REPORTINGVirginia Mercury, “US Supreme Court decision ends Virginia's redistricting fight,” May 18, 2026: voters approved the amendment April 21, 2026 (51.69% to 48.31%); the Supreme Court of Virginia struck it down May 8 because no election intervened between the legislature's two votes; the U.S. Supreme Court denied a stay. virginiamercury.com →
16.REPORTINGVotebeat, “Supreme Court ends Missouri congressional map uncertainty before November election,” September 11, 2026: Missouri votes in November under its 2022 map; the 2025 map is suspended until voters decide the referendum. votebeat.org →
17.RESEARCHCook Political Report, “Introducing the 2026 Cook PVI: Re-Redistricting Yields a More Republican, Less Elastic House Map,” David Wasserman, July 29, 2026. The Cook Partisan Voting Index is computed from the 2020 and 2024 presidential results and was updated for the ten states with new lines; districts with a PVI between D+5 and R+5 fell from 87 to 77, and the median seat moved from R+1 to R+3. cookpolitical.com →
A partisan-lean index, not a race rating and not an election result. The release's date, its ten-state count, and the median's move to R+3 were read from Cook's page on September 13, 2026; the 87-to-77 count sits behind Cook's paywall and is taken from Cook's own published summaries of the release.
18.RESEARCHJowei Chen and Jonathan Rodden, “Unintentional Gerrymandering: Political Geography and Electoral Bias in Legislatures,” Quarterly Journal of Political Science 8, no. 3 (2013): 239–269. Compact, equal-population districts drawn without partisan data still produce a seat bias against the party whose voters are concentrated in cities. doi.org → S38

CHANGES TO THIS CASE

September 13, 2026. Corrected an overstatement in the first version: it said no court would stop a legislature from drawing a map to help its own party. Rucho bars only federal courts from partisan-gerrymandering claims; a Utah court applying state law struck the legislature's map as partisan in November 2025. Dated and defined the Cook figures, cited California's certified Statement of Vote, and attributed the LULAC v. Perry quotation to Justice Kennedy's solo section rather than to the Court.
September 13, 2026. Reframed the page around the question people actually search: what gerrymandering is. Added a plain definition and a worked example, cut the chronology, the state-by-state table, the standalone objection section, and the scorecard box, and moved the site's proposal into a single labeled panel. The research behind the removed material is retained in the project's editorial notes and remains linked from the repair page.

Published September 13, 2026. Last substantive update September 13, 2026. Load-bearing facts last re-verified against primary records September 13, 2026. This page is updated in place when the subject changes; it is not republished as a new article.