Partisan districting and the adoption of proportional representation: gerrymandering and its discontents

Electoral engineering strategies in majoritarian electoral systems, in particular the possibility to contain insurgent parties by manipulating electoral districts for partisan gain, are key determinants of parties’ positions on the adoption of proportional representation (PR). Providing both qualitative and quantitative evidence, this paper demonstrates that partisan districting can be an effective strategy to protect incumbent parties’ dominant political positions. In addition, it shows how insurgent parties push for the adoption of PR to end the practice of partisan districting. Finally, it demonstrates that incumbents – in the face of increasing electoral threats – cling to the existing majoritarian system if partisan districting allows them to influence vote-seat distortions in their favor. Together, these findings suggest that the possibility to contain insurgent parties by means of partisan districting is an important but overlooked alternative to the adoption of PR. Moreover, by demonstrating that vote-seat distortions moderate the relationship between district-level electoral threats and legislators’ support for PR adoption, this paper offers an important corrective to Stein Rokkan’s influential electoral threat thesis.