Cities can be thought of as the absence of physical space between people and firms. As such, they exist to eliminate transportation costs for goods, people and ideas and transportation technologies dictate urban form. In the 21st century, the dominant form of city living is based on the...

Are the well-known facts about urbanization in the United States also true for the developing world? We compare American metropolitan areas with comparable geographic units in Brazil, China and India. Both Gibrat's Law and Zipf's Law seem to hold as well in Brazil as in the U.S., but China and...

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...

Industrial revolution is fundamentally linked with the rise of factories and the decline of skilled artisans in manufacturing. Most scholars agree that factories as compared to artisan shops were intensive in unskilled labor. Indeed, the hallmark of the early factories is the utilization of...

The 1990s were an unusually good decade for the largest American cities and, in particular, for the cities of the Midwest. However, fundamentally urban growth in the 1990s looked extremely similar to urban growth during the prior post-war decades. The growth of cities was determined by three...

The fast and often chaotic urbanization of the developing world generates both economic opportunity and challenges, like contagious disease and congestion, because proximity increases both positive and negative externalities. In this paper, we review the expanding body of economic research on...

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 develop a dynamic microsimulation model to project the labor force and economic dependency ratios in the United States from 2022 to 2060, taking population projections and the large inequalities between population groups of different race/ethnicity and gender into account. We contrast policy...

New York has been remarkably successful relative to any other large city outside of the sunbelt and it remains the nation's premier metropolis. What accounts for New York's rise and continuing success? The rise of New York in the early nineteenth century is the result of technological changes...