Chapter 3 How Interstate Highways Created Republican Suburbs

Policies that change space can change politics, and one way they do so is by facilitating geographic partisan sorting, the tendency for Americans to live in enclaves of like-minded citizens. Standard models attribute the pattern of such changes almost entirely to the aggregate effect of individual citizens’ homophily: the natural tendency of citizens to be drawn to and cluster with similar individuals. I present an alternative account that suggests that government policies that influence mobility also can influence citizens’ personal calculus of residential location. Using historical geographic data to estimate geographic outcomes consistent with this hypothesis, I examine the effects of Interstate Highway System on the political development of suburban communities. Combining construction data from the Interstate Highway System with county-level presidential election data for the years 1948-2008, I show that suburban communities with Interstate highways became as much as five points more Republican than they would have been in the absence of freeway construction–a large enough effect to change a swing district to a landslide district. A metropolitan case study based on Wisconsin precinct-level data and a multi-election national analysis of county-level data shows that such political effects emerge quickly after freeway construction, especially in previously undeveloped areas. These findings demonstrate that federal policies can change politics not only by directly influencing individual welfare, but also by influencing residential choice and the spatial relationships among citizens. Policies that change geographic space can change politics. Even as scholarship on the influence of social policy on politics has taken root in political science (e.g., Pierson 1993; Campbell 2003), we still know remarkably little about the political impacts of one of the oldest forms of social policy: the construction of roads and highways. Highways can change politics not only by providing distributive benefits to selected groups in the geographies where they are located, but also by increasing mobility and remaking the political map. Though treated primarily as mere “pork-barrel” distributive goods in much of the recent political science literature, highways pervasively influence the communities in which they are built. In rural areas, highways make land more attractive to residential development, increasing the growth of politically homogeneous, single-family residential subdivisions more likely to house Republican voters. As a de facto subsidy to suburban home construction, highways appear to have indirectly promoted the growth of voters more likely to be sympathetic to policies and politics that support suburban development.1 The substantial localized impact of highways makes them a social policy–one that happens to provide mobility to different groups of citizens and indirectly affects communities by redistributing the benefits of mobility to different groups. Considerable research in fields from economics to urban planning has demonstrated the social and economic effects of highway construction. Highways stimulate economic development in rural communities (Chandra and Thompson, 2000), have uprooted and destroyed neighborhoods inside cities (Mohl, 2004), and appear to have accelerated suburbanization (Baum-Snow, 2007). Scholars of urban planning, sociology and geography have shown that highways and other major roads split up neighborhoods, producing different development patterns and street behavior patterns after they are built (Grannis, 1998; Noonan, 2005). In this chapter, I posit that one consequence of highway construction is geographic partisan sort1As Gans (1991) writes, “Housing for affluent whites is subsidized by F.H. A. , by tax deductions for home ownership, by federal grants for highway programs that take the suburbanite to and from his downtown job, and by urban renewal. ” (349). The role of highways and other transportation in housing affordability has been well developed in the literature since the 1960s. See Meyer, Kain and Wohl (1971) for a classic study on the relationship of housing development to transportation system design.