Does non-partisan voter mobilization affect the popular vote? We use vote records from a state-level participatory budgeting vote in Brazil– the world’s largest –to assess the impact of voter mobilization messaging on turnout and support for public investments. The government provided records as to how each ballot was cast and designed the tabulation process so that votes could be matched to treatment assignment without compromising the secrecy of the ballot. Citizens (n=43,384) were randomly assigned to receive non-partisan email and text messages designed to encourage voting. We document an impressive 4.7 percentage point increase in online voting in our treatment group. However, we found no effect of messaging on vote choice; voters in the treatment and control groups shared the same sectoral preferences and showed no difference in the average cost of public investment projects they supported. These results suggest non-partisan Get Out the Vote campaigns can increase citizen participation without skewing the outcome.

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