How Gerrymandering Works

Gerrymandering Gets Sophisticated

Because of its long history, gerrymandering conjures up an image of old-school political bosses gathering in smoke-filled rooms to twist arms and dicker over who gets which precincts, as they draw the borders of districts on paper.

But those days are long gone. Redistricting has become a technologically complex affair, shaped by political consultants who roam the country and guide state legislators in redrawing political maps with the help of sophisticated software that processes population data to draw and tinker with hypothetical maps [source: Draper].

To critics of gerrymandering, the Wisconsin state legislative map being reviewed by the U.S. Supreme Court in Gill v. Whitford is a prime example of how technology has made things even worse. As University of Wisconsin mathematics professor Jordan Ellenberg detailed in a New York Times opinion piece, after Republicans gained control of the Wisconsin statehouse in the 2010 election, they used computer algorithms to test how various possible legislative maps would perform in future election scenarios. The result, according to Ellenberg, was a map "precisely engineered to assure Republican control in all but the most extreme circumstances."

The Wisconsin map is designed so ingeniously that if the proportion of Democratic votes rises above 50 to 52 percent, it actually becomes even more skewed toward the Republicans [source: Hershlag, Ravier and Mattingly]. In order to wrest away control of the Assembly, Democrats would have to defeat Republicans at the polls by a statewide margin of eight to 10 points — hardly doable in state split evenly between the two major parties [source: Ellenberg].

But high-powered computing and intricate math work both ways. While political map-makers can use those tools to create maps with the maximum amount of unfairness, it's also possible for political scientists and mathematicians to use the same tools to show that a gerrymandered map is a true outlier — that is, one that's so far outside the ordinary, it was obviously drawn up just to create a partisan advantage.