It was an abomination to democracy, critics said. The popular vote was nearly evenly split between the two parties, yet one party won 29 of the 40 seats at stake. The reason was a creative redrawing of electoral districts—what we now know as gerrymandering.

The practice dates back to the earliest days of the country—it’s even older than Congress—and it’s still alive and well today. In June 2017, the U.S. Supreme Court agreed for the first time to hear a case involving what’s alleged to be purely political gerrymandering in Wisconsin. (The Court has previously heard gerrymandering cases where race was a factor.) But the term itself originates with the lopsided election described above, which