Who Counts the Nation’s Jails?

The Bureau of Justice Statistics (BJS) conducts a Census of Jails to gather information about jail facilities and jurisdictions. Its questionnaires distinguish among jurisdiction-level reporting, facility reporting and multi-jurisdiction facilities. That structure helps explain why counting facilities can be complicated.

BJS calls the Census of Jails its primary data collection on local jails and "the only collection that enumerates all local jails." For families who rely on national jail statistics, knowing where those numbers come from is the first step toward reading them well.

What the Census of Jails collects

According to BJS, the census gathers information on:

• ✱Characteristics of people held, including sex, race, Hispanic origin, citizenship, juvenile status, conviction status and holds for other jurisdictions
• ✱Admissions, releases and average daily population
• ✱Facility characteristics such as capacity, staffing and programs

Some topics rotate from year to year to reduce the reporting burden on jails. BJS administers the census as a web-based survey, with RTI International serving as the data collection agent. About 2,900 local jails and federal detention facilities are surveyed, and BJS reports a 94% response rate for 2024.

The census covers city, county, regional and private local jails, along with Federal Bureau of Prisons detention facilities that function as jails. It excludes juvenile-only facilities, temporary holding facilities that are not part of a general jail, Indian country jails and detention facilities in seven combined prison-jail systems. BJS runs a separate Survey of Jails in Indian Country.

A periodic count that became annual

For decades, the census was conducted every five to six years. BJS lists collections in 1970, 1972, 1978, 1983, 1988, 1993, 1999, 2005/2006, 2013, 2019 and 2024. Beginning in 2024, the census moved to an annual schedule, which BJS says will "provide more timely state-level statistics."

How it relates to the Annual Survey of Jails

For years without a census, BJS's yearly jail figures came from a smaller survey. From 1982 to 2023, the Annual Survey of Jails sampled approximately one-third of the nation's jails, drawing its sample from the Census of Jails. That list of all jails is known as a sampling frame. The census also serves as the frame for other BJS surveys, including the Survey of Inmates in Local Jails and the National Inmate Survey.

According to BJS's Jail Inmates in 2024 statistical tables, the Annual Survey of Jails was discontinued when the census moved to annual collection. That report draws on the 2019 and 2024 Census of Jails along with Annual Survey of Jails data for 2014 to 2018 and 2020 to 2023. Because the census counts all jails rather than a sample, BJS notes its estimates are not subject to sampling error, although they can still be affected by jails that do not respond.

Why the counting gets complicated

The census forms reflect how jails are actually organized. BJS has used a jurisdiction-level form; a form for the central data reporter in jurisdictions with multiple facilities that have separate staff and budgets; and a facility-level addendum for those individual facilities. In 1999, it also used separate forms for multi-jurisdiction facilities operated by two or more governments, privately operated facilities and jails in Indian country.

As a result, any count of jails depends on what is being counted. The 2024 statistical tables, for example, describe 2,765 active jail reporting units as of midyear 2024, of which 2,597 responded. A reporting unit is not necessarily one building or one county.

What this means for families

When you see a national jail number, the Census of Jails is usually where the story begins. You can read about the program on the BJS Census of Jails page, and researchers can find codebooks and datasets through the National Archive of Criminal Justice Data.

For a specific facility, national data are only part of the picture. Use our find a facility directory for contact details and read reviews for firsthand perspectives. Inmate Reviews does not inspect or verify facilities.