During the 1918–1919 influenza pandemic, many local authorities made the controversial decision to close schools. We use newly digitized data from newspaper archives on the length of school closures for 165 large U.S. cities during the 1918–1919 flu pandemic to assess the long-run consequences of closing schools on children. We find that the closures had no detectable impact on children's school attendance in 1920, nor on their educational attainment and adult labor market outcomes in 1940. We highlight important differences between the 1918–1919 and COVID-19 pandemics and caution against extrapolating from our null effects to modern-day settings.