Job Market Paper

Abstract: In the post World War II period, most U.S. cities experienced large movements of population from the city centers to the suburbs. In this paper we provide causal evidence that this process of suburbanization can be explained by the rise of violent crime in city centers. We do so by proposing a new instrument to exogenously predict violent crime. This instrument uses as time variation the U.S. national levels of lead poisoning. Cross-sectional variation comes from a proxy for soil quality, which explains the fate of lead in soil and its subsequent bioavailability. Using data for more than 300 U.S. cities, results show that the increase in violent crime from the level in 1960 to its maximum in 1991 decreased the proportion of people living in city centers by 15 percentage points. This increase in crime moved almost 25 million people to the suburbs.  As a result of suburbanization, we find that people remaining in the city center are more likely to be black people, consistent with the `"white flight" phenomenon. We then demonstrate that this suburbanization process had aggregate effects on the city. Exploiting a spatial equilibrium model, we determine that violent crime had externalities on productivity and amenities.

Online Appendix

Working papers

Abstract: Urbanization is creating important threats to urban development in terms of housing affordability and optimal geographic concentration of people and firms inside the city. This research aims at establishing the different consequences of taller or more spread out cities using a strategy that combines reduced form estimation with a more structural approach. I build a general spatial equilibrium model that allows me to obtain theoretical predictions of the impact of building height and total city size on wages, house prices and population, and to map reduced form elasticities to welfare considerations. Reduced form elasticities have obtained using IV techniques, employing as instruments geological, geographical and technological variables, and exploiting a panel database of U.S. observations at housing level.  Results suggest that both vertical and horizontal increase of a city are associated with a positive increase in housing density and house prices, and no statistically significant effect on wage. However, increasing a city vertically have higher effect on house prices with respect to increasing it horizontally. These reduced form estimates are consistent with a model in which building height and city size have a similar positive effect on city-specific productivity, and height has stronger positive effect on city-specific amenities than city size.

Abstract: This paper explores how urban structure and building height can play an important role for agglomeration and the consequent productivity advantages, looking at the role of skyscraper in influencing the concentration of establishments in U.S. cities. In addition to productivity advantages associated to this extreme form of density, skyscraper can be a particularly attractive location for firms because of the associated gains in prestige from being located in a tall landmark building. Exogenous variation has been obtained instrumenting the completion of new skyscrapers by the interaction between the distance to bedrocks in one ZIP area with the Global steel price. One of the most important results is that the effect of newly completed skyscraper on agglomeration differs between sectors. The attraction of establishments on the ZIP codes where tall buildings will be completed has an important anticipatory component. Evidence of small congestion effects cannot be rejected. Exploiting the variation of firm's density produced by tall buildings, my estimation suggests that agglomeration economies provided by tall buildings might provide an additional 20 percent increase in productivity. That is, I estimate that firms' productivity elasticity to density is 0.04, while the additional productivity elasticity if the firm locate in a skyscraper is 0.01.

Work in progress

  • Gentrifying cities: evidence from San Francisco (with Hasin Yousaf)