......................................................................................................................................................................................................................................................................................................................... doi:10.1017/S1049096516001608 © American Political Science Association, 2016 PS • October 2016 755 Politics Presidential Primary Turnout 1972–2016 Lonna Rae Atkeson, University of New Mexico Cherie D. Maestas, University of North Carolina, Charlotte ABSTRACT We explore the implications of sequential presidential primary elections for turnout in selecting the presidential party nominees. Drawing from a micro-level theory of participation in sequential elections, we develop a set of aggregate-level hypotheses that tease out different ways that candidate mobilization efforts as well as the legal and institu- tional structures within a sequential contest influence turnout in presidential nomination contests. Using data from all state primary elections from 1972–2016, we find that elector- ates facing winnowed candidate pools, and those with contests after the effective endings to presidential contests have substantially reduced turnout that effectively disenfranchises voters in many states. Sequenced primary elections lead to lower overall turnout and less meaningful participation for many voters during presidential nominations contests. W hat role does sequential voting have on turnout? The US presidential nominating system, in 2016, has come under increased scrutiny as candidates, voters, and the news media have criticized its complicated legal design and how variation in state party rules may affect election outcomes. The current system was first implemented in 1972 when new party rules, among other things, connected outcomes at first tier selection events such as caucuses or primaries to candidate delegate counts and ensured that partisans wanting to participate had access to the selection process (Mandate for Reform 1970). This led to greater participation of rank-and-file party members and more internal party democracy in selecting the party nomi- nee, in part, because many states moved from a caucus to a pri- mary to satisfy the new rules resulting in grater turnout (Atkeson and Maestas 2009). However, the sequential nature of the pres- idential nomination process encourages or discourages primary participation depending on the dynamics of the race. We develop a theoretical framework for understanding how the dynamics of a sequential process influences state-level turnout and test our hypotheses using state and party level data from 1972–2016. In doing so, we advance our understanding of primary turnout over prior studies conducted in the early 1980s when the current system was still in its infancy (Norrander 1986c, 1992; Moran and Fenster 1982; Ranney 1977; Norrander and Smith 1985). SEQUENTIAL NOMINATION CAMPAIGNS AND VOTER INCENTIVES Explanations for voter turnout that are rooted in standard rational choice model are poorly suited for predicting turnout in presidential nomination contests at either the individual or aggregate-level because they treat elections as a one-shot contest in which the expected value of a vote cast is derived from the like- lihood of it being pivotal in determining whether one’s candidate wins or loses. Sequential elections are different. Vote shares in earlier elections serve not only to determine winners and losers of specific contests, but also serve as signals to voters in subsequent contests about the viability, or nominatability, of candidates. Therefore, voters can be “pivotal” in a broader sense by contrib- uting to a candidate’s momentum by helping a candidate to meet or exceed expectations set in the media or by helping a candidate to expand his or her delegate count. The micro-foundation of aggregate nomination turnout is the individual-level decision to vote or abstain and depends on the expected utility of her vote at the time at which the vote is cast. This value differs for voters in different positions in the electoral sequence because the value of votes cast later in the sequence depends on the outcomes earlier in the sequence (Battaglini 2005). Like other vote choice models, we assume that the institu- tional costs of voting and election mobilization influence the vote calculus as well, but the timing of the vote relative to the pool of candidates remaining is paramount to the choice to vote because the effective costs and benefits vary across the sequence of the election. Mobilization by active candidate organizations reduces the informational and time costs of voting, but the incentives for candidates to engage in mobilization change because the race is dynamic. In addition, the degree to which candidates other than the frontrunner still have a reasonable chance of winning affects their potential value as a voting signal. The dynamics of dele- gate accumulation across the sequential contests influence the chances that subsequent votes influence candidate viability. The uniform exposure of voters in each state to the sequential position of their race in the overall nomination process allows us to form expectations for aggregate differences in turnout across states based on assumptions about the micro-level effects Lonna Rae Atkeson is professor in the department of political science at the University of New Mexico. She may be reached at atkeson@unm.edu. Cherie D. Maestas is professor in the department of political science at the University of North Carolina, Charlotte. She may be reached at cmaestas@uncc.edu.