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.
Annual Survey of Jails: Non-certainty jurisdictions (CJ-5)
Annual Survey of Jails: Certainty Multi-jurisdiction or Private Facility (CJ-5da)
Annual Survey of Jails: Non-certainty Private Facility (CJ-5a)
Annual Survey of Jails: Certainty jurisdictions (CJ-5d)
Annual Summary on Inmates Under Jail Jurisdiction: Multi-jurisdiction or Private Facility (CJ-10A/5)
Prior to 2015, the ASJ asked jails to report the total and detailed inmate counts on the last weekday in June (the midyear reference date). In 2015 and 2016, the ASJ collected the total confined population at midyear but detailed inmate counts by characteristics (i.e., sex, race or ethnicity, age category, conviction status, and most serious type of offense) on December 31 (the year-end reference date). Starting with the 2017 collection, the ASJ reverted back to the midyear reference. Comparisons of year-end data with midyear data need to consider seasonal variations, as jails typically hold fewer inmates at year-end than at midyear.