Effects of State Legislative Redistricting Methods on Competitiveness and Polarization

Abstract

Political redistricting methods have been blamed for rising political polarization and falling electoral competitiveness in the House of Representatives. Despite widespread condemnation of gerrymandering in the media, scholarly studies of redistricting methods have failed to reach a consensus on whether the redistricting method a state uses is related to polarization or competitiveness. Study of state legislatures, which are collectively larger than the House of Representatives and are individually self-contained, could help answer these questions. Until recently, data on state legislative elections and polarization was sparse and low in quality, but new data sets published in the past few years have changed this. Using these new data, I use regression analysis to test whether the redistricting method a state uses has an effect on state legislative polarization or competitiveness. Explanatory charts showing trends are also included. I find a small but significant difference in competitiveness between states with political redistricting methods and states with non-political redistricting methods. In contrast, I find that polarization is significantly lower in states with political redistricting methods, the exact opposite of theoretical expectations. Discussion of possible reasons for this unexpected result follows.