Your vote is (no) secret! How low voter density hurts anonymity and biases elections in Italy

How do electoral outcomes change when the perception of ballot secrecy falters? We answer this question in the context of Italy, where voters are assigned to polling stations according to their address and candidates know how many votes they receive in each polling station. When the number of voters per polling station (voter density) is low, this jeopardises the secrecy of voting and gives politicians an instrument to tightly monitor people. Exploiting variation in voter density across cities and over time, combined with rich data on the results of local elections across all Italian municipalities between 1989 and 2015, we estimate the effect of voter density on electoral competition. We find that when voter density is lower (and secrecy is at greater risk), politicians who are already in office (and can wield stronger retaliatory power) are more likely to retain their post. The analysis addresses the potential endogeneity of voter density. The results are stronger in regions with lower social capital and worse institutions.