Voter turnout has declined in many industrialized countries, raising the question of whether electoral institutions increase voter turnout. We exploit an electoral reform in the Austrian state of Burgenland as a natural experiment to identify the causal effect of opening hours of polling stations on voter turnout. The results show that a 10 percent increase in opening hours increased voter turnout by some 0.5 to 0.9 percentage points. The effect is substantial because voter turnout was already around 80 percent before the reform in question. The results also show that the vote share of the conservative party decreased in the course of the reform, while the vote shares of the social democratic party and of the populist rightwing party (both parties attract blue-collar workers) increased. Enhancing participation in elections by extending the opening hours of polling stations remains a question to what extent politicians and voters believe that the benefits of higher voter turnout overcompensate for additional costs of longer opening hours.