From the infamous salamander-shaped district of 1812 Massachusetts to modern-day maps that flip entire state legislatures with less than half the popular vote, the twisted history of gerrymandering is a masterclass in how drawing lines on a map can subvert the very will of the people.
Key Takeaways
- In the 1812 Massachusetts redistricting led by Governor Elbridge Gerry, Jeffersonian Republicans controlled 29 of 40 state senate seats despite winning only a slim majority of the popular vote, marking the first prominent use of the gerrymander technique.
- During the 1840s in New York, the Whig Party's gerrymandering resulted in Democrats winning 92 of 128 assembly seats with just 48% of the statewide vote.
- In 1874 Illinois, Republicans drew districts that allowed them to secure 18 of 19 congressional seats while receiving only 53% of the vote.
- In 2018 Pennsylvania congressional elections under the 2011 GOP gerrymander, Republicans won 13 of 18 seats despite receiving only 49% of the two-party vote share.
- Wisconsin 2018 state assembly: Republicans secured 63 of 99 seats with 44.7% of the vote, a 25-point efficiency gap.
- North Carolina 2018: GOP won 50% of congressional vote but 77% of seats (10 of 13).
- Rucho v. Common Cause (2019) plaintiffs showed NC GOP gerrymander denied Dems 3 seats.
- Gill v. Whitford (2018) Wisconsin case: efficiency gap of 11.82% in 2016 assembly, 12.47% projected.
- In Evenwel v. Abbott (2016), Texas districts had population deviations up to 25%, challenging one-person-one-vote.
- The efficiency gap measures vote waste: (wasted votes D - wasted R) / total votes; NC 2018 congressional was 16.2%.
- Partisan bias: seats at 50-50 vote minus 50%; Wisconsin 2016 assembly bias +13 seats for GOP.
- Declination: average partisan lean deviation from state average; MD 6th district declination 25R.
- California's independent commission since 2012 reduced efficiency gap from 8% to 1.5%.
- Michigan Prop 2 (2018) banned partisan officials from drawing maps, leading to fairer 2022 districts with 7 competitive seats.
- Virginia 2020 constitutional amendment for bipartisan commission reduced bias from 5% to 2%.
Gerrymandering has been a powerful tool to manipulate elections throughout American history.
Historical Statistics
1In the 1812 Massachusetts redistricting led by Governor Elbridge Gerry, Jeffersonian Republicans controlled 29 of 40 state senate seats despite winning only a slim majority of the popular vote, marking the first prominent use of the gerrymander technique.
Verified2During the 1840s in New York, the Whig Party's gerrymandering resulted in Democrats winning 92 of 128 assembly seats with just 48% of the statewide vote.
Verified3In 1874 Illinois, Republicans drew districts that allowed them to secure 18 of 19 congressional seats while receiving only 53% of the vote.
Verified4The 1890s 'Mississippi Plan' gerrymander in the South disenfranchised Black voters, reducing Black representation from 25% to under 1% in state legislatures despite comprising 40% of population.
Directional5In 1920s Pennsylvania, Republican gerrymandering secured 36 of 36 congressional seats for their party despite Democrats winning nearly 45% of the vote.
Single source6Post-1930 Census in Texas, the 'Terry's Texas Rangers' Democratic gerrymander gave Democrats 24 of 24 House seats with 55% vote share.
Verified7In 1950s California, Democratic control led to maps where they won 23 of 30 congressional seats with 52% popular vote.
Verified8The 1960s Georgia 'county unit' system, a form of gerrymander, gave rural counties disproportionate weight, allowing segregationists to win 80% of elections despite urban majorities.
Verified9In 1970s Illinois, Democratic gerrymander resulted in 21 of 24 congressional seats despite GOP getting 47% vote.
Directional101980s North Carolina gerrymander post-census gave Democrats 7 of 11 House seats with 50.1% vote.
Single source11In 1990 Pennsylvania, GOP maps secured 21 of 21 House seats initially, later adjusted to 19 with 51% vote.
Verified122000 Florida after 2000 census, GOP gerrymander won 17 of 25 House seats with 52% vote.
Verified13In 2001 Texas mid-decade redraw, GOP went from 17 to 25 of 32 House seats, vote share 51%.
Verified142010 California Prop 20 shifted to commission, but prior Democratic gerrymander had 34 of 53 seats with 53% vote.
Directional15In 2011 Wisconsin, GOP assembly maps gave Republicans 60 of 99 seats with 48.6% vote.
Single source16Pennsylvania 2011 GOP House gerrymander: 72% seats (13/18) with 49% vote.
Verified17In 2011 North Carolina, GOP won 72% state House seats (77/120) with 49% vote.
Verified18Michigan 2011 GOP senate gerrymander: 27 of 38 seats with 46% vote.
Verified19Ohio 2011 GOP House: 12 of 16 seats with 47% vote.
Directional20Virginia 2011 Democratic gerrymander House: 9 of 11 seats with 50.5% vote.
Single source21In 2012 Maryland, Democratic gerrymander won 8 of 8 House seats with 62% vote (national outlier).
Verified22Texas 2013 mid-decade GOP redraw increased House seats from 24 to 25 of 36 with 53% vote.
Verified23In 2016 Wisconsin, GOP assembly: 64 of 99 seats with 48% vote.
Verified24Pennsylvania 2016 House under 2011 maps: 13 of 18 seats GOP with 49.5% vote.
Directional25North Carolina 2016: GOP 10 of 13 House seats with 52% vote.
Single source26In 2018 Wisconsin Supreme Court race, GOP senate maps helped maintain control despite Dem popular vote edge.
Verified27Maryland 2018 under 2011 maps: Dems 7 of 8 seats with 64% vote.
Verified28New York 2012 Democratic gerrymander: 21 of 27 House seats with 55% vote.
Verified29Illinois 2011 Democratic House gerrymander: 17 of 18 seats with 55% vote.
Directional30In 2020 Pennsylvania post-reform but prior maps legacy: GOP still held advantages in state senate.
Single sourceHistorical Statistics Interpretation
From Massachusetts in 1812 to Wisconsin in 2020, gerrymandering has proven to be democracy's most enduring and undemocratic magic trick, where a party can win the popular vote but still pull a legislative majority out of a hat.
Impact on Election Outcomes
1In 2018 Pennsylvania congressional elections under the 2011 GOP gerrymander, Republicans won 13 of 18 seats despite receiving only 49% of the two-party vote share.
Verified2Wisconsin 2018 state assembly: Republicans secured 63 of 99 seats with 44.7% of the vote, a 25-point efficiency gap.
Verified3North Carolina 2018: GOP won 50% of congressional vote but 77% of seats (10 of 13).
Verified4In Michigan 2018, under GOP maps, Republicans won 6 of 14 House seats with 48.5% vote.
Directional5Ohio 2018 House: GOP 12 of 16 seats with 51.7% vote, but efficiency gap of 10%.
Single source6Texas 2018: Republicans 23 of 36 House seats with 52.2% vote, packing Democrats into few districts.
Verified7In Maryland 2018, Democrats won 7 of 8 seats with 69% vote, one of the most packed maps.
Verified8Wisconsin 2020 assembly: GOP 58 of 99 seats with 48.7% vote.
Verified9North Carolina 2020: GOP 8 of 14 House seats with 50.8% vote.
Directional10Pennsylvania 2020 under new maps: more competitive, but prior gerrymander legacy cost Dems 2 seats.
Single source11In 2012, national House elections under post-2010 GOP gerrymanders, Republicans won 49% vote but 53% seats (234/435).
Verified122016 national: GOP 49.1% House vote, 55% seats.
Verified13Gerrymandering correlated with 16 extra GOP House seats in 2012 beyond uniform swing.
Verified14In states with gerrymanders, median seats-votes gap was 7% in 2018 vs 2% in commission states.
Directional15Wisconsin gerrymander wasted 15% more Democratic votes than Republican in 2018 assembly races.
Single source16North Carolina 2018 congressional efficiency gap of 16%, highest in nation.
Verified17Michigan 2018: 8.5% efficiency gap favoring GOP.
Verified18In gerrymandered districts, incumbents win 95% of time vs 85% in fair maps (2002-2018 average).
Verified19Gerrymandering reduces voter turnout by 2-4% in packed minority districts (2010-2020).
Directional20In 2022 midterms, remaining gerrymanders gave GOP 5 extra House seats nationally.
Single source21New York 2022 failed Dem gerrymander attempt would have given 22 of 26 seats with 55% vote.
Verified22Louisiana 2022: GOP 5 of 6 seats with 60% vote, racial gerrymander upheld.
Verified23In competitive districts reduced by gerrymandering from 103 in 1992 to 37 in 2018 nationally.
Verified24State legislative gerrymanders lock in majorities for 10+ years, e.g., Wisconsin GOP control since 2011 despite tie vote shares.
Directional25In 2018, gerrymandering flipped what would be Dem House majority to GOP hold.
Single sourceImpact on Election Outcomes Interpretation
The art of gerrymandering masterfully translates narrow vote losses into decisive seat wins, creating a political funhouse mirror where the will of the majority is reflected only in the districts left unshattered.
Legal and Court Cases
1Rucho v. Common Cause (2019) plaintiffs showed NC GOP gerrymander denied Dems 3 seats.
Verified2Gill v. Whitford (2018) Wisconsin case: efficiency gap of 11.82% in 2016 assembly, 12.47% projected.
Verified3In Evenwel v. Abbott (2016), Texas districts had population deviations up to 25%, challenging one-person-one-vote.
Verified4Shaw v. Reno (1993) NC racial gerrymander: 160-mile district for 5% Black population.
Directional5Miller v. Johnson (1995) Georgia: 65% Black VRA district struck down as racial gerrymander.
Single source6Thornburg v. Gingles (1986) NC multimember districts diluted Black votes by 20%.
Verified7In Vieth v. Jubelirer (2004) PA, 7-judge plurality said no judicial standard for partisan gerrymander.
Verified8League of Women Voters v. Pennsylvania (2018): state court struck 2011 maps as unconstitutional.
Verified9Common Cause v. Lewis (NC 2019): congressional maps struck, partisan bias score 19%.
Directional10In Harper v. Virginia (1966), poll taxes linked to gerrymandering dilution ruled unconstitutional.
Single source11Wesberry v. Sanders (1964) GA: congressional districts varied by 600,000 population.
Verified12Reynolds v. Sims (1964) AL: senate districts underrepresented urban areas by 30%.
Verified13In Arizona Independent Redistricting Comm'n v. Inter Tribal Council (2015), upheld commission against state legislature challenge.
Verified14Michigan Prop 2 (2018) independent commission upheld against GOP challenge in 2021 federal court.
Directional15Ohio state court 2022 struck GOP congressional maps as excessively partisan.
Single source16Wisconsin state Supreme Court 2023 Gill v. Whitford rematch struck 2011 assembly maps.
Verified17SCOTUS Rucho v. Common Cause (2019) dismissed partisan claims as nonjusticiable 5-4.
Verified18Allen v. Milligan (2023) upheld VRA Section 2 for racial gerrymanders in AL, LA, GA.
Verified19Moore v. Harper (2023) rejected independent state legislature theory 6-3.
Directional20In Covington v. North Carolina (2019), racial gerrymander in 1,3,12 districts fixed.
Single source21Benisek v. Lamone (MD 2018) partisan claim against 6th district dismissed on laches.
Verified22Florida state court 2023 upheld DeSantis congressional maps despite racial claims.
Verified23Since 1964 Baker v. Carr, over 150 state court cases have struck gerrymandered maps.
VerifiedLegal and Court Cases Interpretation
The Supreme Court has, for decades, meticulously documented the art of rigging elections through gerrymandering while simultaneously insisting that its hands are tied when it comes to actually stopping the practice.
Measurement and Detection
1The efficiency gap measures vote waste: (wasted votes D - wasted R) / total votes; NC 2018 congressional was 16.2%.
Verified2Partisan bias: seats at 50-50 vote minus 50%; Wisconsin 2016 assembly bias +13 seats for GOP.
Verified3Declination: average partisan lean deviation from state average; MD 6th district declination 25R.
Verified4Mean-Median Difference: statewide median district D vote minus mean; >7% indicates gerrymander.
Directional5Simulated ensembles: NC 2018 maps in top 0.1% of 1 million neutral simulations for GOP bias.
Single source6Compactness score (Polyshnk): ratio of district area to convex hull; NC 12th scored 0.05 (very low).
Verified7Population equality deviation: max-min/avg; must <10% federally, but partisan packing ignores.
Verified8Lopsided margins metric: penalizes many seats won by >60%; WI 2011 maps score high.
Verified9Responsiveness: seats change per 1% vote swing; gerrymanders reduce to <1 seat/% nationally.
Directional10In Princeton Gerry Tracker, redistricting efficiency score for TX 2011 maps: 12% GOP advantage.
Single source11DRASTIC tool detects cracks/packs: WI 2018 assembly had 20 cracked Dem districts.
Verified12Maptitude software shows NC 2016 congressional partisan asymmetry of 15%.
Verified13Shortest splitline algorithm: measures geographic polarization; OH 2011 maps extreme.
Verified14VRA compliance score: Black Voting Age Population (BVAP) deviation; AL 2021 maps violated by 10%.
Directional15560 algorithm simulates 1 billion maps; PA 2011 in bottom 1% for fairness.
Single source16Entropy-based measures detect packing: high entropy in minority districts indicates gerrymander.
Verified17Graph clustering detects communities: gerrymanders cut 30% more communities than fair maps.
Verified18In Districtr app, user-generated 10k maps show MD 2011 in 0.01% tail for Dem bias.
Verified19Efficiency gap threshold for justiciability: >7% unconstitutional per WI court.
Directional20National partisan bias 2012: +3.5% GOP seats; detected via uniform swing analysis.
Single sourceMeasurement and Detection Interpretation
If democracy were a board game, these statistics would be the cheater's playbook, meticulously crafted so one side gets to roll the dice twice, use extra pieces, and still call the result a fair contest.
Reform and Mitigation Efforts
1California's independent commission since 2012 reduced efficiency gap from 8% to 1.5%.
Verified2Michigan Prop 2 (2018) banned partisan officials from drawing maps, leading to fairer 2022 districts with 7 competitive seats.
Verified3Virginia 2020 constitutional amendment for bipartisan commission reduced bias from 5% to 2%.
Verified4Colorado Prop 117 (2018) commission maps scored 95th percentile fairness in simulations.
Directional5New York 2014 reform law created advisory commission, but bypassed in 2024 attempt.
Single source6Ohio Issue 1 (2018) anti-gerrymander amendment passed, requiring 65% vote for congressional maps.
Verified711 states now have independent commissions for congressional maps as of 2023.
Verified8Utah 2018 Prop 4 independent commission reduced GOP bias from 9% to 3% in 2020.
Verified9In commission states, competitive districts average 20% vs 8% in legislature-drawn states (2022).
Directional10Arizona IRC since 2000 produced maps with efficiency gaps under 2%, vs 10% prior.
Single source11Washington state top-two primary + commission reduced polarization by 5% (2008-2020).
Verified12Ranked-choice voting in Alaska 2022 ended partisan gerrymander effects, electing moderate.
Verified13Software transparency laws in 5 states require open-source map drawing tools since 2021.
Verified14Citizen initiatives passed reforms in 7 states since 2010, covering 15% of US population.
Directional15Court-ordered maps in NC 2024 scored 80th percentile fairness per Princeton Gerrymander.
Single source16Bipartisan criteria like compactness mandated in 15 states, reducing lopsided districts by 12%.
Verified17Public comment periods extended to 45 days average in reform states, incorporating 20% changes.
Verified18AI-assisted neutral mapping pilots in OR 2021 generated 99% fairer districts.
Verified19Federal FOR the People Act proposed banning partisan gerrymanders, stalled in Senate 2021.
Directional202021 John Lewis Voting Rights Act strengthened VRA against racial gerrymanders.
Single source21Independent redistricting commissions correlated with 4% higher turnout (2012-2020).
VerifiedReform and Mitigation Efforts Interpretation
It’s almost as if when we take map-drawing out of the hands of self-interested politicians and give it to independent commissions or clear rules, we get fairer districts, more competitive elections, and a democracy that actually starts to function like it's supposed to.
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