Comparing the Effects of Legislative, Commission, and Judicial Redistricting Plans on U.S. House Elections, 1972-2002

Following a series of Supreme Court decisions in the 1960s, the states were required by law to redraw legislative and congressional district boundaries. During the past 40 years, states have adopted a variety of methods for redistributing internal population shifts and taking into account the addition or elimination of existing seats. In this paper, we examine how differences in redistricting plans have affected the competitiveness of U.S. congressional elections. Specifically, we focus on three commonly employed methods for redrawing districts: legislative, independent commission, and judicial plans. We find that the degree of electoral competition generally increases when commissions or courts are responsible for drawing new legislative districts. Moreover, we find a distinct pattern in partisan differences in redistricting strategy when Democratic or Republican controlled state governments seek to offset their minority party status in the U.S. House of Representatives. The effects vary when we control for the number of seats gained or lost in each state