Diffusion and spatial equilibrium of a social norm: voting participation in the United States, 1920–2008

Social conformity can spread social norms and behaviors through a society. This research examines such a process geographically and over time for voting, which is strongly influenced by the norm that citizens should vote. A mathematical model for the spread of voting participation under the influence of social conformity is developed based on the diffusion equation, and predictions are tested with spatial analysis of state-level voter turnout in American presidential elections from 1920 to 2008. Results show that voter turnout has converged to a stable equilibrium in its geographical distribution across the states—but it is an equilibrium that results in persistent differences at the state level. Results are compared to individual-level and agent-based models. The model may be applied to other types of social diffusion that depend on specific geographical location. Copyright Springer Science+Business Media Dordrecht 2014