Fig. 2.

Relationship between Distance from Boston (thousands of miles) and NPIs (years of implementation). Note: The sample is for 45 U.S. cities. Distance from Boston is the minimum distance shown by Google Maps. Non-Pharmaceutical Interventions (NPIs) from September 1918 to February 1919 are from Markel et al. (2007, Table 1), updated to include Atlanta and Detroit. NPIs are days in effect (in units of years) for school closings, prohibitions of public gatherings, and quarantine/isolation. See Appendix Table A1.