I examine the relationship between labor unions and voter turnout in the American states. Though it is well known that unions increase turnout directly, we know less about their indirect effects. Moreover, the indirect effects may consist of nonmember mobilization and aggregate strength. To examine the direct and indirect mechanisms, I analyze both state-level panel data and individual-level data with a multilevel approach. First, my panel analysis shows that unions are positively associated with turnout as expected. Yet, the association is observed only in midterm elections, but not in presidential elections. Second, more importantly, my individual-level analysis suggests that indirect nonmember mobilization and indirect aggregate strength are positively related to turnout, while direct member mobilization is not. The findings imply that the direct effects are limited and, thus, that decreasing levels of voter turnout due to recently declining union membership come primarily from indirect mobilization rather than direct mobilization.
