Technology
How Gerrymandering Affects Representation in Congress
Quick fact
In the 2012 U.S. House elections, Democrats won about 1.4 million more votes nationally than Republicans, yet Republicans won a 33-seat majority in the House—a gap largely attributed to gerrymandering.
Why this is interesting
Imagine you could draw the map of your neighborhood so that you always win the block party vote. In America, each decade, the people in power get to redraw the congressional map to do exactly that.
Read the full explanation
Understanding How Gerrymandering Affects Representation in Congress
Congressional districts are the geographic areas that elect members of the House of Representatives. Every ten years, after the census, states redraw these district boundaries to account for population shifts. The people who draw these lines—usually state legislators—can choose to draw them in ways that help their own party. This process is called gerrymandering. There are two main techniques. 'Cracking' spreads a party's supporters across many districts so they are a minority in each, wasting many of their votes. 'Packing' concentrates a party's supporters into a few districts, giving them overwhelming majority but limiting their influence elsewhere. Both techniques are designed to create districts where the favored party wins comfortably, reducing overall representation for the other party.
A deeper explanation
The mechanism of gerrymandering works because representation is based on winning individual districts, not on the total vote. By manipulating the geographic distribution of voters, a party can turn a statewide minority into a majority of seats. This is possible because voters are not randomly distributed—they tend to cluster by demographics and location. The key is the concept of 'wasted votes': votes cast for a losing candidate and excess votes for a winning candidate (votes beyond what is needed). In a gerrymandered system, a party deliberately creates districts where the opponent's votes are wasted. For example, if a party packs its opponent's supporters into one district, it wins that district with, say, 90% of the vote, but those extra votes are 'wasted' because they don't contribute to winning other districts. Similarly, cracking can waste opponent votes by splitting them so they lose each district. This is why gerrymandering is often described as 'voters choosing their representatives' vs. 'representatives choosing their voters.' It matters because it undermines the principle of majority rule and can make elections uncompetitive, reducing accountability and increasing polarization.