Once a relatively obscure phenomenon, gerrymandering is having its moment. In the past year, there have been legal challenges to election district lines in Wisconsin, Maryland, North Carolina and in our home state of Pennsylvania. Regardless of the outcome of these cases, it’s clear the methods we use to draw our political maps are broken. Where new maps are drawn by state legislatures, majority parties have few checks on their ability to shape districts as they please, creating a circular process that keeps them in power, even when winning a minority of statewide votes. One alternative is to give responsibility to independent commissions, as states such as Alaska, Arizona, California, Idaho, Montana and Washington have done. But this solution hinges on having workable procedures to identify truly independent commissioners who can resist manipulation from savvy politicians.
There’s another way to solve the problem — one that draws fairer maps by leveraging the competition between Democrats and Republicans rather than by developing mechanisms to circumvent it. And it is as simple and intuitive as dividing up a cake.
Even children eventually learn that there is an easy and fair method for dividing a good between two people. To share a cake, one child can divide the cake into two pieces he views as equally desirable, and then the second child can choose her preferred slice. This classic “I cut, you choose” protocol guarantees the fairness of the outcome: The first child is indifferent between the two pieces, so he is happy with his share. And the second child is obviously content because she receives her preferred piece.