Partisan Conversion Through Neighborhood Influence: How Voters Adopt the Partisanship of Their Neighbors

Recent studies show that American neighborhoods have become politically homogeneous, raising concerns about how geographic polarization divides parties and influences voters. But, it remains unclear how voters are influenced by the politics of their neighbors. I argue that voters are influenced by local norms when defining their own partisan affiliations, adopting local partisanship. Panel data on 41 million voters from 2008 to 2020 and an original survey of 24,433 respondents demonstrate that exposure to partisan neighbors increases party switching. These effects are largest for older voters, voters in single-family communities, and voters with more same-race neighbors. Survey data support mechanisms of social influence: Voters accurately perceive local partisanship, interact more with partisans they live near, and are more comfortable when their partisanship matches neighbors’ political affiliations. Partisanship is thus shaped by where voters live and who they live close to, demonstrating the behavioral consequences of geographic polarization.