When Do Shelter‐in‐place Orders Fight Covid‐19 Best? Policy Heterogeneity Across States and Adoption Time

This study explores the impact of Shelter‐in‐Place Orders (SIPOs) on health, with attention to heterogeneity in their impacts. First, using daily state‐level social distancing data, we document that adoption of a SIPO was associated with a 9%–10% increase in the rate at which state residents remained in their homes full‐time. Using daily state‐level coronavirus case data, we find that approximately 3 weeks following the adoption of a SIPO, cumulative COVID‐19 cases fell by approximately 53.5%. However, this average effect masks important heterogeneity across states‐early adopters and high population density states appear to reap larger benefits from their SIPOs. ( JEL H75, I12, I18)