Gerrymandering, the process of drawing district lines to fortify one political party at the expense of another, is as old as the U.S. republic. In the late 1780s, Virginia Governor Patrick Henry, who opposed ratifying the new Constitution, got allies in his state’s legislature to draw a congressional district map unfavorable to James Madison, the father of the founding document. (Madison won anyway.) Good-government groups grouse that gerrymandering lets politicians choose their constituents, rather than the other way around. But as the courts get more involved, others fret about judges interfering in politics.
The nation’s 435 House districts are adjusted after each decennial census. The goal, as required by the U.S. Supreme Court, is to make sure that, in states with more than one House member, the congressional districts have roughly the same number of people. (State legislative districts are redrawn as well.) Gerrymandering can result in districts being comically shaped to get the right number of people and the hoped-for political breakdown. One district in Pennsylvania is said by critics to resemble the cartoon character Goofy kicking Donald Duck.
There are two primary tactics that governing Party A can use to limit the number of congressional seats Party B can win. One is called “packing,” or cramming many of Party B’s voters into a few districts that it will win overwhelmingly, with many (wasted) votes to spare. The other technique, “cracking,” splinters Party B’s voters among multiple districts so that it can’t prevail in any of them. Using such techniques, a party can turn a narrow lead in statewide voters into a decisive and lasting advantage in a state’s congressional delegation. In North Carolina, for instance, House Republicans in 2016 won 10 of the 13 seats with just 53 percent of the popular vote. Better technology, and more-detailed information about voter preferences, have made gerrymandering an even more potent tool.