In this paper we study the effect of violent crime on residential and firms location decisions and their implications for segregation in cities. We do so by proposing a new instrument to exogenously predict violent crime in city centers. We base our instrument on chemical and medical evidence that links local characteristics of the soil to lead poisoning and aggression. We show that the increase in violent crime between 1960 and 1990 due to lead poisoning moved almost 8 million people to the suburbs. Firms followed by leaving the city centers. We then show that the suburbanization process was characterized by "white flight".

We exploit a unique quasi-experiment to study the effects of judicial decisions on sensitive issues on political attitudes. In 2010, the Spanish Constitutional Court partially overruled the new Catalan Constitution–the Estatut–that granted further decentralization. Our identification strategy relies on the fact that this ruling occurred amid a public opinion survey. We find that the ruling increased support for independence by 5 percentage points. We interpret this result as evidence of judicial backlash on political attitudes: a judicial decision that limited further autonomy triggered a shift in attitudes towards even more autonomy. Moreover, the ruling decreased trust in the courts and satisfaction with democracy. This backlash of political attitudes extends to other spheres: Catalans increased their national identification with their region and the support for pro-decentralization parties. Finally, we show that the ruling increased polarization around the partisan and identity cleavages.

This chapter reviews the recent evidence in Urban Economics on gentrification. The first part of the chapter provides a definition of gentrification and describes recent trends in academic research and popular interest in the topic. The chapter then presents evidence on the causes of gentrification, followed by consequences of gentrification. Four main factors that can spur gentrification in neighborhoods are analyzed: changes in amenities, labor markets, commuting, and housing markets. The chapter then reviews papers showing the consequences of gentrification in six main areas: housing costs, amenities, displacement of poorer households, local employment, health, and human capital accumulation of children. The chapter then summarizes the consequences of gentrification in terms of wage and welfare inequalities between low-income and high-income individuals. The chapter concludes by reviewing the literature that can guide the policy analysis about how to alleviate the housing affordability issues generated by gentrification. Throughout the chapter, avenues for further research are outlined.

Since 2004, Google and other tech firms have introduced bus routes to transport employees from the San Francisco city center to Silicon Valley. This created a shock in commuting costs that uniquely affected tech workers without affecting the rest of the population. We exploit this shock to study the effects of gentrification on local amenities and income segregation. Using a differences-in-differences strategy, we first show that the shock relocated tech workers to the treated neighborhoods--block groups in San Francisco with tech bus stops. We then show evidence of sorting: housing demand by other high-skilled individuals increased in the treated neighborhoods. Treated block groups experienced improved local amenities as measured through revealed preferences--the new residents were willing to pay higher housing costs and accept longer commutes--and directly through improved consumption and public amenities. Although the neighborhood improved because of higher local amenities, the poorest population was displaced.

What explains the geography of new technology adoption? This paper studies technology adoption and factory location in England during the Industrial Revolution. First, we document a negative relationship between industrialization in the nineteenth century and preindustrial economic activities. Second, we show that while cities with self-governing institutions displayed higher preindustrial economic growth, they failed to adopt new industrial technologies during the nineteenth century. We argue that because local self-governance led to the development of representative institutions, this facilitated collective action and enabled workers threatened by labor mechanization to resist technology adoption. Higher resistance to technology adoption, in turn, resulted in the relocation of economic activities away from traditional centers of production. Results suggest that while institutions facilitating collective action foster Smithian growth, they may hinder Shumpeterian growth by increasing resistance to technology adoption.

We exploit the 2022 Russian invasion of Ukraine as a shock to the anti-Russia attitudes in Spain. We collect data from multiple sources: the Spanish NATO referendum of 1986, monthly public opinion surveys with voting and pro-war attitudes, and the universe of political speeches in the Spanish Congress. Using different empirical strategies we robustly identify the effect of the invasion on domestic politics. The three main results are the following: we show that the Russia-Ukraine conflict increased by around 5 percentage points the current intention to vote for the main center-right party (Partido Popular--PP) among the individuals in the municipalities that strongly supported NATO in the 1986 referendum. Similarly, in those municipalities, individuals have lower ``sympathy" for Russia and a stronger perception of the country as a military threat. Finally, the increase in the voting intention for the PP goes hand in hand with the legislators' narrative in Congress: after the invasion, PP legislators are more likely to mention Russia in their speeches, and when they do, they talk more negatively about it.

This paper explores how building height plays an important role in firms' agglomeration and its consequent effects on productivity and overall urban structure. We do this by looking at the role of skyscrapers in influencing the concentration of establishments in U.S. cities. We identify the agglomeration effects of tall buildings instrumenting the completion of new skyscrapers by the interaction between the distance to bedrocks in one ZIP area with the past Global steel price. Results suggest that tall buildings affect the location of firms inside a city. Tall buildings increase both agglomeration of firms in the surrounding areas and their productivity. The effect of newly completed skyscrapers on agglomeration differs between sectors. The attraction of establishments to ZIP codes where tall buildings are built has an important anticipatory component. Exploiting the variation of firms' density produced by tall buildings, we estimate that firms' productivity elasticity to establishment density is 0.05, while the additional productivity elasticity if firms locates in a skyscraper is 0.01.

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.