Should I Mail or Should I Go: Voting Behavior After a One-Time All-Postal Election

We investigate how reducing information costs through forced experimentation with postal voting, while holding administrative rules fixed, affects subsequent voting behavior. Leveraging a natural experiment during Bavaria’s 2020 Mayoral Elections and drawing on municipality-level administrative data spanning seven federal and state elections (2013-2025), we employ an event study design. We find a transitory increase in total turnout of 0.4 percentage points in the first election after the treatment, one and a half years later, and a persistent substitution from in-person to postal voting even five years after the treatment. Municipalities with a higher turnout in the past show larger effects. Investigating the distribution of information costs shows an age gradient, with the highest information costs in the oldest municipalities. The conservative governing party gains from higher postal turnout and other right-wing parties’ in-person voters.