The measurement of partisan sorting for 180 million voters

Abstract

Segregation across social groups is an enduring feature of nearly all human societies and is associated with a host of social maladies. In many countries, reports of growing geographic political polarization raise concerns about the stability of democratic governance. Using advances in spatial data computation, we measure individual partisan segregation by calculating the local residential segregation of every registered voter in the United States, creating a spatially-weighted measure for over 180 million individuals. With these data, we present new evidence of extensive partisan segregation in the United States. A large portion of voters live with virtually no exposure to voters from the other party in their residential environment. Such high-levels of partisan isolation can be found across a range of places and densities and are distinct from racial/ethnic segregation. Moreover, Democrats and Republicans living in the same city --- or even the same neighborhood --- are segregated by party.