Partisan Consequences of the Post-1990 Redistricting for the U.S. House of Representatives

Abstract

Following each recent round of redistricting, scholars have tried to determine whether that round worked to one party's advantage and whether control of the redistricting process by members of one party led to gerrymandering. They have reached mixed conclusions. Here, we examine the partisan consequences of the post-1990 redistricting for the U.S. House of Representatives. We create two sets of projections of partisan support levels for the 1990 and 1992 districts based on district-level 1988 presidential election data. One set of projections assumes an incumbency advantage, and one set assumes the hypothetical situation of all open seats, i.e., no incumbency advantage. We ask whether either party benefited and whether gerrymandering occurred. When we take incumbency into account, we find that our projections show that the two parties came out just about even in redistricting, with an increase in the number of districts evenly split between them. However, when we assume all open seats, our projections show an increase of 21 Republican districts, a decrease of 3 Democratic districts, and a decrease of 17 evenly split districts. We conclude that the Republican party gained from redistricting and that incumbency and other short-term factors obscure changes in the underlying partisan support in districts. In a state-level analysis of redistricting outcomes, we find no evidence that parties succeeded in using control of state government to gain partisan advantage through redistricting.