The Policy Effects of the Partisan Composition of State Government

Source: Devin Caughey, Chris Warshaw, Yiqing Xu, Massachusetts Institute of Technology (MIT) Political Science Department Research Paper No. 2015-24, September 28, 2015

From the abstract:
How much does it matter which party controls the government? There are a number of reasons to believe that the partisan composition of state government should affect policy. But the existing evidence that electing Democrats instead of Republicans into office leads to more liberal policies is surprisingly weak, inconsistent, and contingent. We bring clarity to this debate with the aid of a new measure of the policy liberalism of each state from 1936-2014, using regression discontinuity and dynamic panel analyses to estimate the policy effects of the partisan composition of state legislatures and governorships. We find that until the 1980s, partisan control of state government had negligible effects on policy liberalism, but that since then partisan effects have grown markedly. Even today, however, the policy effects of partisan composition pale in comparison to the policy differences across states. They are also small relative to the partisan divergence in legislative voting records.