Counterfactual Road Networks: A Method for Examining Social and Spatial Division in Road Networks

Racism, discriminatory practices, institutional bias, and systematic exclusion can take lasting physical form in the built environment. There has been growing attention to the long-term consequences of housing policies and practices on social and economic outcomes, including residential segregation, but comparatively less attention to other aspects of the built environment, such as road networks and spatial (dis)connectivity. In this article, the authors introduce a novel method that constructs counterfactual road networks by identifying missing road segments that would be expected to exist in a city’s road network, given the surrounding infrastructure. The authors demonstrate the empirical application of the method by analyzing differences in racial composition and residential segregation for the observed and counterfactual road networks of five U.S. cities. The authors find that unexpected disconnectivity in a city’s road network is associated with greater differences in the racial composition of nearby areas and higher levels of segregation at the local and city levels. The present findings suggest that road networks warrant more attention as a factor that may contribute to the persistence of segregation.