incarceration facility size distribution for U.S. about 2006

The U.S. Bureau of Justice Statistics regularly issues statistics on inmates incarcerated in jails and prisons.  These reports provide inmate populations by incarceration jurisdictions: federal (Federal Bureau of Prisons), state (state Departments of Corrections), and local (jail jurisdictions, usually counties and cities).[1]  Jurisdictions are not the same as physically and administratively separate incarceration facilities.  Within large incarceration jurisdictions are multiple incarceration facilities of widely varying sizes.  For example, the Florida Department of Corrections encompasses about 160 incarceration facilities ranging from ones holding about 2000 prisoners to ones holding under 20 prisoners.  Statistics on the U.S. incarceration facility size distribution, measured by number of inmates held, aren’t readily available in published statistical reports.  The underlying data, however, are publicly available.  To make statistics on the U.S. incarceration facility size distribution more readily available, I’ve compiled the relevant data for about the year 2006 and made it publicly available in a statistics spreadsheet workbook.

Facility shares and inmate shares differ greatly as descriptions of the incarceration facility size distribution.  Most incarceration facilities are small.  Most inmates are held in large incarceration facilities.  For example, 28% of non-federal incarceration facilities each hold under 50 inmates.  They hold in aggregate only 1% of non-federal inmates.  At the other end of the distributions, only 2% of non-federal incarceration facilities each hold 2500 or more inmates.  But those facilities hold in aggregate 18% of all non-federal inmates.

The distinction between jurisdictions and facilities is relevant only for the largest jail jurisdictions.  About 2006, the U.S. had about 3000 jail jurisdictions encompassing about 3300 physically and administratively separate jail facilities.  These jail statistics do not include physically separate temporary holding facilities such as drunk tanks and police lockups that do not hold persons longer than 72 hours or after arraignment.  Many thousands of such very small, temporary incarceration facilities exist.[2]  At the other end of the size distribution of jail jurisdictions are Los Angeles and New York.  Those jail jurisdictions each hold about 20000 inmates and have 9 and 13 separate jail facilities, respectively.[3]

The federal prison system encompasses persons detained on federal charges before case disposition and persons sentenced to incarceration for federal crimes.  Case disposition in the U.S. means in practice either a prosecutor or judge dismissing the case or the defendant making a guilty plea under plea bargaining.  For non-federal charges, jails hold persons detained before case disposition and persons sentenced to short spells of incarceration (typically under a year).  The federal system holds anyone detained or sentenced under federal charges.  While data aren’t readily available on smaller federal incarceration facilities, available data on federal facilities illustrates the variety of incarceration facilities. These include detention centers, work camps, low-security correctional institutions, and high-security penitentiaries.

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Data:  U.S. incarceration facility size distribution (prisons and jails, c. 2006) (Excel version)

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[1] The word inmates tends to be used for persons held in jails, and the word prisoners, for persons held in state and federal prisons.  But inmates and prisoners are also used generically to refer to all persons held in all incarceration facilities.  Here’s more on incarceration terminology.

[2] These facilities are relevant for estimating the number of spells of legal detention for a night or longer.

[3]  The number of jail facilities are based on data reported in the U.S. Census of Jail Facilities, 2006.  That source is the basis for the jail statistics included in the U.S. incarceration facility size distribution.