Suburbanization and highways in Spain when the Romans and the Bourbons still shape its cities

© 2014 Elsevier Inc. We estimate the effects of highways on the suburbanization of Spanish cities. Based on Spain's historical roads - the almost 2000. years old Roman roads and the 1760 Bourbon roads -, we rely on an instrumental variables (IV) strategy because of the endogeneity of highway provision. Our results show that, first, each highway emanating from central cities caused an 8-9% decline in central city population between 1960 and 2011. Second, each highway ray fostered a 20% population growth in the suburbs, in particular in suburban municipalities where ramps were located. Finally, we confirm the increasing role of highways on shaping urban form: each additional kilometer closer to the nearest highway ramp increased municipal density growth by an 8%.