The U.S. has relatively poor national-level data on prisoners (inmates) in jails. Prior to 1970, only the decennial national censuses collected data nationally on jail populations. In 1970, the U.S. Bureau of Justice Statistics established the Census of Jails. It has generally taken place every five years.

Beginning in 1982, the U.S. Bureau of Justice Statistics’ Annual Survey of Jails collected data on jail populations. The data are from a representative survey of jails, rather than comprehensive data reporting.

Statistics are available on prison and jail inmates at midyear / jail inmates at midyear annual publications. Here’s a summary annual time-series of jail inmates from 1983.

Reports online for the Census of Jails: 1983, 1988, 1993, 1999

Reports online based main on the Annual Survey of Jails: 1982, 1984, 1985, 1986, 1987, 1989, 1990, 1991, 1992, 1993-4, 1995, from 1996