Considerable debate exists over the impact of electoral institutions on turnout in U.S. national elections. To address this debate, I exploit the rich variation in electoral rules present throughout the nineteenth and early twentieth century. Using a newly constructed dataset of district-level turnout results for the U.S. House from 1840 to 1940, I find that electoral institutions and political competition jointly provided incentives, and by the turn-of-the-century disincentives, for political leaders to mobilize the electorate. The results demonstrate that changes in electoral institutions and varying levels of political competition help explain congressional turnout across districts and over time.