The Bureau of Justice Statistics (BJS) periodically conducts the COJ, a complete enumeration of local jail jurisdictions and facilities and of the Federal Bureau of Prisons’ (BOP) 12 detention facilities that function as jails. The COJ covers all local jails in 45 states and the District of Columbia. It excludes the combined jail and prison systems in Alaska, Connecticut, Delaware, Hawaii, Rhode Island, and Vermont, but includes 15 independently operated jails in Alaska. Data from the 12 BOP detention facilities that function as jails are not presented in this report. In 2019, BJS included an addendum to the COJ to measure local jail jurisdictions’ OUD screening and treatment practices and the prevalence of screenings and treatment for OUD among persons confined in jail.