Primary Elections and Mail Voting

Objective A problem for US democracy may be very low voter turnout in midterm primary elections, which has been associated with increasing ideological polarization in Congress and state legislatures. Turnout in these elections averages 20% and overwhelmingly represents partisan rather than unaffiliated voters. This study argues that earlier research has underestimated the effects of primary reforms, as it has not accounted for a key mediating factor: the growth in mail‐in voting ballots. Methods Utilizing the 2022 voter file data combined with historical voting data from millions of Americans across all states, this study hypothesizes that open and nonpartisan primaries, along with the availability of mail voting, increase the likelihood of individual turnout in congressional primaries. Results The results indicate that state mail voting laws (universal mail voting or no‐excuse absentee mail voting) and more widespread use of mail voting ballots can boost turnout in primary elections, particularly when combined with open or nonpartisan primary rules. Mail voting implementation—as measured by the percentage of total votes cast by mail—has the largest positive effect on increasing turnout in open or nonpartisan primary states, followed by closed primary states. Conclusion It is important to consider overlapping laws when evaluating election reforms.