The Effect of Electoral Systems on Voter Turnout: Evidence from a Natural Experiment

I exploit the unique institutional framework of Spanish local elections, where municipalities follow different electoral systems depending on their population size, as mandated by a national law. Using a regression discontinuity design, I compare turnout under closed list proportional representation and under an open list, plurality-at-large system where voters can vote for individual candidates from the same or different party-lists. I find that the open list system increases turnout by between 1 and 2 percentage points. The results suggest that open list systems, which introduce competition both across and within parties, are conducive to more voter turnout.