Divided government, polarization, and policy: Regression-discontinuity evidence from US states

In this paper we use data on US states and a regression-discontinuity design to study how divided government affects the polarization of the legislature, inter-branch conflict, and policy implementation. We document that Republican legislators serving under a divided government have more conservative ideologies than those serving under a fully unified government. Correspondingly, Democrats have more liberal ideologies. In terms of policy implementation, however, we find evidence of moderation: compared to unified Republican governments, divided ones with a democratic governorship or senate implement more liberal policies. When Democrats lose unified control, instead, policies become more conservative.