City limits and partisan sorting

To what extent does variation in access to local governance explain partisan sorting in the USA? Prior research shows that voters do not sort into neighborhoods based on partisan concerns alone. However, political attitudes are related to many residential preferences such as tastes for local public goods, making partisanship alone a weak treatment. To overcome this limitation, this study exploits discontinuous changes in the provision of municipal public services at the institutional boundaries between incorporated and unincorporated areas. Examining the near-universe of US cities, this study documents a decline in electoral support for Democrats in areas just outside city limits. The gap in partisanship is particularly prominent outside major metropolitan areas but is less detectable in states where the contrast in local governance between cities and their outskirts is weaker. Using geolocated voter registration data, this study shows that partisan sorting is related not only to a city’s demographic and socioeconomic characteristics but also to its taxation and expenditures. These findings shed new light on how the contours of local political institutions inform geographic partisan sorting.