*Values are no. (%) except as indicated. HHS, US Department of Health and Human Services; ID, identification; IQR, interquartile range; K, kindergarten; NCES, National Center for Education Statistics; PSS, the Private School Universe Survey. †School years: 2020–21 (July 27, 2020–June 30, 2021), 2021–22 (August 1, 2021–June 30, 2022). ‡School closures were defined as a transition from being opened to being closed for in-person instruction excluding any scheduled days off; fully in-person and hybrid learning modalities were classified as open, and fully remote and closed were classified as closed. Closure events were documented at either the district-level or the individual school level on the basis of the source and scope of the closure decision as reported in the announcements. §Schools were counted once for each time they were part of a school closure event at either the district-level or school level. ¶Number of schools closed in district-wide closures, total number of students, total number of teachers, number of students eligible for federal free or reduced-priced lunch, and number of schools by urbanicity and grade levels were estimated by matching the public school district ID or public school ID with the district or school data with the respective year, as obtained from NCES and private school ID with the 2019–20 private school data, as obtained from PSS. Because of missing information on urbanicity in 2021–22 NCES public school data, the information on urbanicity for the 2021–22 school year public school closures was obtained from the 2020–21 NCES public school data (6,7). School NCES ID was not found for 168 schools (124 for 2020–21 school year and 44 for 2021–22 school year), which were categorized as public or private by manual search on the basis of the location of schools in the school closure announcements. #HHS regions defined at https://www.hhs.gov/about/agencies/regional-offices/index.html. **Students were counted once for each school closure event. The number of students was missing for 562 schools (public, 325; private, 237). ††Teachers were counted once for each school closure event. Part-time teaching positions were reported as a fraction of 1 full-time position. The number of teachers was missing for 1,041 schools (public, 804; private, 237). ‡‡Data only for public schools. §§In-person student-days lost estimated by multiplying the number of students per school by the number of unplanned closure days. ¶¶2,075 schools did not have reopening dates and defaulted to a 1-day closure; among these, 1,996 (96%) were during the 2020–21 school year.