We find that a firm's investment is highly sensitive to the investments of other firms headquartered nearby, even those in very different industries. It also responds to fluctuations in the cash flows and stock prices (q) of local firms outside its sector. These patterns do not appear to reflect...

American cities have experienced a remarkable renaissance over the past 40 years, but in recent years, cities have experienced considerable discontent. Anger about high housing prices and gentrification has led to protests. The urban wage premium appears to have disappeared for less skilled...

We develop an urban growth model where human capital spillovers foster entrepreneurship and learning in heterogenous cities. Incumbent residents limit city expansion through planning regulations so that commuting and housing costs do not outweigh productivity gains. The model builds on strong...

The downsides of density, including traffic congestion, contagious disease and crime, were common in Victorian London and classical Rome, just as they are today in Sao Paulo and Lagos. Our urban past provides lessons for developing world cities today. The first lesson, that I highlight, is that...

We examine "agglomeration shadows" that emerge around large cities, which discourage some economic activities in nearby areas. Identifying agglomeration shadows is complicated, however, by endogenous city formation and "wave interference" that we show in simulations. We use the locations of...