We use a panel of county-level location data derived from cellular devices in the U.S. to track travel behavior and its relationship with COVID-19 cases in the early stages of the outbreak. We find that travel activity dropped significantly as case counts rose locally. People traveled less overall, and they specifically avoided areas with relatively larger outbreaks, independent of government restrictions on mobility. The drop in activity limited exposure to out-of-county virus cases, which we show was important because such case exposure generated new cases inside a county. This suggests the outbreak would have spread faster and to a greater degree had travel activity not dropped accordingly. Our findings imply that the scale and geographic network of travel activity and the travel response of individuals are important for understanding the spread of COVID-19 and for policies that seek to control it.

This paper studies the effects of marijuana legalization on neighborhood crime using unique geospatial data from Denver, Colorado. We construct a highly local panel data set that includes changes in the location of marijuana dispensaries and changes in neighborhood crime. To account for endogenous retail dispensary locations, we use a novel identification strategy that exploits exogenous changes in demand across different locations. The change in geographic demand arises from the increased importance of access to external markets caused by a change in state and local policy. The results imply that retail dispensaries lead to reduced crime in the neighborhoods where they are located. Reductions in crime are highly localized, with no evidence of benefits for adjacent neighborhoods. The spatial extent of these effects are consistent with a policing or security response, and analysis of detailed crime categories provides indirect evidence that the reduction in crime arises from a disruption of illicit markets.

Congestion costs in urban areas are significant and clearly represent a negative externality. Nonetheless, economists also recognize the production advantages of urban density in the form of positive agglomeration externalities. The long-run equilibrium outcomes in economies with multiple correlated but offsetting externalities have yet to be fully explored in the literature. Therefore, I develop a spatial equilibrium model of urban structure that includes both congestion costs and agglomeration externalities. I then estimate the structural parameters of the model using a computational algorithm to match the spatial distribution of employment, population, land use, land rents, and commute times in the data. Policy simulations based on the estimates suggest that congestion pricing may have ambiguous consequences for economic welfare.

Congestion costs in urban areas are significant and clearly represent a negative externality. Nonetheless, economists also recognize the production advantages of urban density in the form of positive agglomeration externalities. The long-run equilibrium outcomes in economies with multiple correlated but offsetting externalities have yet to be fully explored in the literature. Therefore, I develop a spatial equilibrium model of urban structure that includes both congestion costs and agglomeration externalities. I then estimate the structural parameters of the model using a computational algorithm to match the spatial distribution of employment, population, land use, land rents, and commute times in the data. Policy simulations based on the estimates suggest that congestion pricing may have ambiguous consequences for economic welfare.

This paper studies the effects of marijuana legalization on neighborhood crime using unique geospatial data from Denver, Colorado. We construct a highly local panel data set that includes changes in the location of marijuana dispensaries and changes in neighborhood crime. To account for endogenous retail dispensary locations, we use a novel identification strategy that exploits exogenous changes in demand across different locations. The change in geographic demand arises from the increased importance of access to external markets caused by a change in state and local policy. The results imply that retail dispensaries lead to reduced crime in the neighborhoods where they are located. Reductions in crime are highly localized, with no evidence of benefits for adjacent neighborhoods. The spatial extent of these effects are consistent with a policing or security response, and analysis of detailed crime categories provides indirect evidence that the reduction in crime arises from a disruption of illicit markets.