After an intense, year-long examination of the public health response of 43 American cities during the 1918-1919 epidemic, researchers at the Center for the History of Medicine and the CDC concluded that those cities that used social distancing measures and other non-pharmaceutical interventions (NPI) in 1918 fared better than those that did not. More specifically, we found a strong association between early, sustained, and layered use of NPI and mitigating the consequences of the epidemic.