A behavioral measure of the enthusiasm gap in American elections

What are the effects of a mobilized party base on elections? I present a new behavioral measure of the enthusiasm gap in a set of American elections to identify how the turnout rate of the party faithful varies across different contexts. I find that the advantaged party can see its registrants turn out by four percentage points more than the disadvantaged party in some elections, and that this effect can be even larger in competitive House districts. I estimate the net benefit to party vote share of the mobilized base, which is around one percentage point statewide, and up to one and one half points in competitive House contests. These results suggest that the partisan characteristics of an election have consequences not just for vote choice, but for the composition of the electorate.