Partisan Connection in Context: Explaining the Online and Offline Political Homophily in American Counties

Political homophily has been extensively examined as an individual tendency, but we know little about the social, cultural, and economic conditions that foster homophilic connections. We offer a contextual explanation of political homophily and shed light on spatial polarization from a social-communication network perspective by combining GLMNet models, spatial lag regressions, and geographically weighted regressions to examine various ecological factors’ roles in the political homophily observable in county-level physical mobility and Facebook friendship networks. Overall, our analyses suggest that urban culture characterized by large population, robust local news provision, racial-ethnic diversity, and progressive political culture tend to foster politically inclusive connections. More specifically, the proportion of Democrats is strongly associated with more cross-cutting connections, both online and offline. While population size is associated with lower offline homophily, racial-national diversity and local news availability play more important roles in lowering online homophily. Geographical contexts matter in the way people socialize with one another, even in the era of internet and social media.