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The Politics of Policy: The Initial Mass Political Effects of Medicaid Expansion in the States



Whether public policy affects electoral politics is an enduring question with an elusive answer. We identify the impact of the highly contested Patient Protection and Affordable Care Act (ACA) of 2010 by exploiting cross-state variation created by the 2012 Supreme Court decision in National Federation of Independent Business v. Sebelius. We compare changes in registration and turnout following the expansion of Medicaid in January of 2014 to show that counties in expansion states experience higher political participation compared to similar counties in nonexpansion states. Importantly, the increases we identify are concentrated in counties with the largest percentage of eligible beneficiaries. The effect on voter registration persists through the 2016 election, but an impact on voter turnout is only evident in 2014. Despite the partisan politics surrounding the ACA–a political environment that differs markedly from social programs producing policy feedbacks in the past—our evidence is broadly consistent with claims that social policy programs can produce some political impacts, at least in the short-term.


Corresponding author

Joshua D. Clinton is the Abby and Jon Winkelried Chair and Professor of Political Science, Vanderbilt University, PMB 505, 230 Appleton Place, Nashville, TN 37203-5721 (
Michael W. Sances is an Assistant Professor of Political Science, University of Memphis, 421 Clement Hall, Memphis, TN 38152 (


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Helpful reactions were provided by seminar participants at Vanderbilt, UCLA, Princeton University, Yale University, and the University of British Columbia. This article has been supported in part by Award No. 94-16-06 from the Russell Sage Foundation. All opinions and errors are our own.



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The Politics of Policy: The Initial Mass Political Effects of Medicaid Expansion in the States



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