Before revision:  We combine publicly available data sources on the timing of stay-at-home orders and daily confirmed COVID-19 cases  at the county level in the United States (N = 124,027). We then derive from the classic SIR model a two-way fixed-effects model and apply it to the data with controls for unmeasured differences between counties and over time. Mean county-level daily growth in COVID-19 infections peaked at 17.2\% just before stay-at-home  orders were issued.
After revision:  We combine publicly available data sources on the timing of stay-at-home orders and daily confirmed COVID-19 cases at the county level in the United States . We estimate the effect of stay-at-home orders were issued.