Each new radial highway serving large U.S. metropolitan areas decentralized 14% to 16% of central city working residents and 4% to 6% of jobs in the 1960–2000 period. Model calibrations yield implied elasticities of central city total factor productivity to central city employment relative to suburban employment of 0.04 to 0.09, meaning a large fraction of agglomeration economies operates at submetropolitan-area spatial scales. Each additional highway causes central city income net of commuting costs to increase by up to 2.4% and housing cost to decline by up to 1.3%. Factor reallocation toward land in housing production generates the plurality of the population decentralization caused by new highways.

We investigate how urban railroad and highway configurations have influenced urban form in Chinese cities since 1990. Each radial highway displaces 4% of central city population to surrounding regions, and ring roads displace about an additional 20%, with stronger effects in the richer coastal and central regions. Each radial railroad reduces central city industrial GDP by about 20%, with ring roads displacing an additional 50%. We provide evidence that radial highways decentralize service sector activity, radial railroads decentralize industrial activity, and ring roads decentralize both. Historical transportation infrastructure provides identifying variation in more recent measures of infrastructure.

A strong positive monotonic relationship between wage inequality and city size developed between 1979 and 2007 in the United States. After accounting for differences in skill composition across cities of different sizes, we find that at least 23% of the nationwide increase in the variance of log hourly wages is explained by the more rapid growth in wage inequality in larger locations than in smaller locations. This influence occurred throughout the wage distribution, was most prevalent during the 1990s, and was mostly driven by more rapid growth in within-skill-group inequality in larger cities.