We estimated the COVID-19 burden in adult correctional or detention facilities and associated counties by state, facility jurisdiction, and county urbanicity. COVID-19 cumulative incidence (cases per 1,000 persons) for each U.S. correctional or detention facility and people ages 18 years and older in the associated county was estimated between January 1, 2020 and July 20, 2021. Across 46 U.S. states, 1,083 correctional or detention facilities in 718 counties were included. The median COVID-19 incidence rate was higher in facilities than in associated counties for 42 of 46 states and for all facility jurisdictions and county urbanicity categories. COVID-19 burden was higher in most facilities than in associated counties. Implementing COVID-19 mitigation measures in correctional settings is needed to prevent SARS-CoV-2 transmission in facilities and associated counties.