What is gerrymandering?
Gerrymandering means drawing voting district boundaries to favor a political party or group. The lines change which voters compete for the same seat, giving some voters more influence over election results than others.
Two common methods are packing voters together and cracking them apart. The Brennan Center’s gerrymandering explainer describes both methods and why district shape alone can mislead.
Is all redistricting gerrymandering?
No. Redistricting means redrawing district boundaries to reflect population changes, usually after the census every ten years. Gerrymandering uses that process to give a party or group an unfair advantage. Maps can also change between censuses.
These lines affect U.S. House districts, state legislative districts, and some local elections. U.S. senators represent whole states, not districts within a state. Either party can gerrymander when it controls the map.
How do packing and cracking work?
Imagine 300 voters across three districts, with 100 voters in each. Party A has 120 supporters and Party B has 180. Everyone votes for their party, and the candidate with the most votes wins each seat.
Packing: crowd voters together
Mapmakers concentrate opposing voters in a few districts. Those voters win by large margins there but have less influence elsewhere.
Put 90 Party A voters in one district and 15 in each of the other two. Party A wins one of three seats, despite its landslide in that district.
Cracking: split voters apart
Mapmakers divide opposing voters among several districts. Those voters become a minority in each district and struggle to elect their preferred candidates.
Put 40 Party A voters in each district, against 60 Party B voters. Party A wins zero of three seats, despite having the same 120 supporters.
These simplified counts explain the methods, not a real map. Actual maps must account for geography, population, and legal rules. Mapmakers can combine packing and cracking in one map.
Can you tell by the shape?
Shape alone does not prove gerrymandering. An unusual boundary may follow a river, a city border, or a community. A tidy-looking district can still pack or crack voters. A lopsided result alone does not prove gerrymandering either. Where voters live also affects election results.
Find your district. Follow the votes.
Your district helps decide who represents you in the House. Their votes help decide federal law. The district guide shows how to find your current district through the official House lookup.
A ZIP code can cross district lines. Use your home street address in the official House lookup to confirm your district. An upcoming election may use different boundaries. Check your state or local election office for the district on your ballot.