Mercury Rising: How State Policy Diffusion Influences National Public Opinion

This dissertation examines the relationship between state policy diffusion and related national public opinion over time. Specifically, I ask whether state-level policy activity can influence national opinion where a policy diffuses sufficiently to encompass a majority of citizens. Although scholars have identified the linkage between policy activity and public opinion at the national level and within the states, the dynamics of this relationship across levels within the American federal system remain largely unexplored. Consequently, our understanding of public opinion on a host of issues in politics – such as gay marriage, abortion, crime policy, and gun control – remains incomplete. There is reason to suspect, however, that where issues are acted upon at the national and subnational levels, related opinion is influenced by the policy activities of both systems. In this dissertation, I offer a new dynamic underlying public opinion change in the United States, the diffusion-opinion-linkage, which reveals the influence of state policy diffusion on related national opinion over time. I analyze this relationship by leveraging temporal and geographic variation in the passage of “shall-issue” concealed carry laws in the states from 1990-2010. I assess the effects of shall-issue debate, passage, and policy feedback on individual attitudes, state-level opinion, and national measures, finding a clear relationship between the diffusion of this policy and growing national gun policy conservatism over time. I conclude by discussing how this study contributes to the public opinion and diffusion literatures, with a recommendation that the individual and collective dynamics of the diffusion-opinion-linkage be considered when evaluating the connection between policy activity and public opinion in future work.