How Much Does COVID-19 Increase With Mobility? Evidence From New York and Four Other US Cities

How effective are restrictions on mobility in limiting COVID-19 spread? Using zip code data across five U.S. cities, we estimate that total cases per capita decrease by 20% for every ten percentage point fall in mobility. Addressing endogeneity concerns, we instrument for travel by residential teleworkable and essential shares and find a 27% decline in cases per capita. Using panel data for NYC with week and zip code fixed effects, we estimate a decline of 17%. We find substantial spatial and temporal heterogeneity; east coast cities have stronger effects, with the largest for NYC in the pandemic’s early stages.