School reopened in August-September 2020 and their effect on COVID-19 infections is unclear. Methods: We examined Coronavirus Disease-19 incidence following school reopening in Florida. Results: We found that counties teaching physically had 1.2-fold incidence increase in elementary schools and 1.3-fold increase in high schools, while counties teaching remotely had no increase. Conclusions: Our results suggest that counties teaching physically could consider teaching remotely, especially in high school, until it is safe to teach physically.