Before revision: In March and April 2020, public health authorities in the United States acted to mitigate transmission of COVID-19. These actions were not coordinated at the national level  , which creates an opportunity to use spatial and temporal variation to measure their effect with greater accuracy.
After revision: Governments issue "stay at home" orders to reduce the spread of contagious diseases, but the magnitude of such orders' effectiveness is uncertain. In the United States these orders were not coordinated at the national level , which creates an opportunity to use spatial and temporal variation to measure their effect with greater accuracy.