Annual Survey of Jails (ASJ)

The Bureau of Justice Statistics (BJS) periodically conducts census data collections from all local jails in the United States. In years between census collections, BJS conducts the Annual Survey of Jails (ASJ). The survey collects data annually from a sample of local jails and uses the data to estimate the number and characteristics of inmates in local jails nationwide.

The ASJ uses a stratified probability sampling design based on jail population data collected through the most recent Census of Jails (COJ). Jails in the ASJ sample are surveyed annually until the next sample is drawn. The ASJ sample is drawn at the jail jurisdiction level. When a jail jurisdiction with multiple jail operators or facilities is sampled, data are collected from all reporting units within that jail jurisdiction. The most recent sample refresh occurred in the 2020 ASJ, where a sample of 899 jail jurisdictions was selected to represent the approximately 2,850 jail jurisdictions nationwide. In selecting jails, all jurisdictions were grouped into 10 strata based on their inmate population and the presence of juveniles at midyear 2019. In 8 of the 10 strata, a random sample of jail jurisdictions was selected. The remaining two strata were certainty strata, where all jail jurisdictions were selected. One certainty stratum consisted of all jails that were operated jointly by two or more jurisdictions. The other certainty stratum consisted of large jail jurisdictions that—

• held at least one juvenile inmate and a total of 500 or more inmates on June 28, 2019 or
• held 750 or more adult inmates on June 28, 2019.

See Methodology in each report for details specific to the collection in the Jail Inmates at Midyear series.

For methodologies prior to the 2006 ASJ, refer to the National Archive of Criminal Justice Data.