Evaluating Missouri's New Districting Law: Can it Reliably ID "Better" Maps?

• In Event: Election Law in the States

Abstract

In 2018 Missouri’s voters overwhelmingly passed a ballot initiative requiring a nonpartisan “state demographer” to draw their state’s legislative maps with the primary goal of minimizing the disparity of wasted votes between the two major parties under a variety of electoral circumstances spelled out by the statute. This unusual marriage of process with a specific standard for mapmakers is promising, but the standard required – a variation of Stephanopoulos and McGhee’s “Efficiency Gap” – raises questions about its reliability. In this this essay, we examine Missouri’s current legislative map, widely suspected of being a gerrymander, with the help of 1,000 neutral maps drawn by computer using the test prescribed by Missouri’s districting law to determine if we are able to identify a singular map or set of maps which appear best under the various circumstances required by the law. Our results show that different maps, including the current, enacted map, fare better under different circumstances, suggesting that Missouri’s new law cannot reliably identify “better” maps according to its own terms.

Authors

• Jonathan S. Krasno, Binghamton University

• Gregory Robinson

• Shawn J Donahue, University at Buffalo