A key reason for the existence of cities are the externalities created when people cluster together in close proximity. During Covid, such interactions came with health risks and people found other ways to interact. We document how cities changed during Covid and consider how the persistence of...

We explore the impact of rising incomes at the top of the distribution on spatial sorting patterns within large U.S. cities. We develop and quantify a spatial model of a city with heterogeneous agents and non-homothetic preferences for neighborhoods with endogenous amenity quality. As the rich...

This paper shows that the products and prices offered in markets are correlated with local income-specific tastes. To quantify the welfare impact of this variation, I calculate local price indexes micro-founded by a model of non-homothetic demand over thousands of grocery products. These indexes...

Tracking human activity in real time and at fine spatial scale is particularly valuable during episodes such as the COVID-19 pandemic. In this paper, we discuss the suitability of smartphone data for quantifying movement and social contact. We show that these data cover broad sections of the US...

We study the causes of “nutritional inequality”: why the wealthy eat more healthfully than the poor in the United States. Exploiting supermarket entry, household moves to healthier neighborhoods, and purchasing patterns among households with identical local supply, we reject that...

This paper documents and explains the striking rise in the proclivity of college-educated individuals to reside near city centers since 2000. We show that this recent urban revival is driven almost entirely by younger college graduates in larger cities. With a residential choice model, we...

This paper uses detailed barcode data on purchase transactions by households in 49 U.S. cities to overcome a large number of problems that have plagued spatial price index measurement. We identify two important sources of bias. Heterogeneity bias arises from comparing different goods in...

Official price indexes, such as the CPI, are imperfect indicators of inflation calculated using ad hoc price formulae different from the theoretically well-founded inflation indexes favored by economists. This paper provides the first estimate of how accurately the CPI informs us about "true"...

Using novel data describing the healthfulness of household food purchases and the retail landscapes consumers face, we measure the role of access in explaining why wealthier and more educated households purchase healthier foods. We find that spatial differences in access, though significant, are...