Election Day Registration and Same Day Registration in State Legislative Districts

Decades of research into the effects of voter registration requirements on turnout has found that voter registration disproportionately suppresses turnout among marginalized racial and socioeconomic groups that traditionally are represented by the Democratic Party. Research also shows that enacting Same Day or Election Day Registration (EDR/SDR) increases voter turnout for Democratic candidates in national elections. The conclusion drawn has been that EDR/SDR increases the representation of marginalized groups. The study in this paper challenges these findings in three ways. First, although EDR/SDR results in a larger total democratic vote, the claims of increased representation may be overstated. This study of the effects of SDR/EDR on turnout in individual state legislative districts finds that both Republican and Democratic state legislators experience vote gains after EDR or SDR are implemented. Second, if EDR/SDR increases Democratic representation then it should result in Democratic gains against Republican candidates on a district-by-district basis. This study will show that these gains are by no means certain and may even result in net gains in the Republican voteshare in state legislative districts. Third, previous studies of the effects of EDR/SDR on partisan turnout and voteshares have not included the ideological leanings of the district. This study shows that that a district’s ideology score influences the effects of EDR/SDR on partisan turnout and voteshares both separately and by interacting with EDR/SDR. Finally, a series of difference-in-difference models confirms that the basic findings of the effects of EDR/SDR on voteshare hold when the model is modified to account for changes to EDR/SDR law over time.