A jail is a secure facility that houses three main types of inmates:
- People who have been arrested and are being held pending a plea agreement, trial, or sentencing;
- People who have been convicted of a misdemeanor criminal offense and are serving a sentence of (typically) less than 1 year; and
- People who have been sentenced to prison and are about to be transferred to another facility.
Jails are operated by a county or city government. Jails are also known as detention facilities. Lockups are facilities in smaller communities where one to a few arrestees can be held for a short time pending transfer to a nearby jail/detention center.
A lot of new detainees are delivered to jails daily. Some may stay less than one day or only for a few days, until they are okayed for release in a court proceeding. Some are released after putting up bail, are released to a pretrial services caseload, are placed under supervision by a probation agency, or are released on their own recognizance with an agreement to appear in court.
A considerable number of people arriving at a jail are actively or recently drunk or high, arrive with injuries from fights/assaults that led to their arrest, and/or are mentally ill with no other place for law enforcement to deliver them. This makes the intake process challenging for the jail’s staff and its medical personnel.
A prison is a secure facility that houses people who have been convicted of a felony criminal offense and are serving a sentence of (typically) 1 year or more.
Prisons are operated by a state government or the federal government. “Penitentiary” is a synonym for prison.
The number of sentenced inmates entering prisons each day is far less than the number of people delivered at the door of U.S. jails. People who are going to prison know it in advance. They may be transferred from a jail, taken to prison from court after a conviction, or report to prison on a date set by the court.
People released from prison may be released to parole supervision or to some other type of community program. Or they may be released with no supervision at all, if they have served their full term in prison.
Where the definitions get fuzzy:
- In Pennsylvania, some county jails are known as county prisons.
- In six states, a state-level agency provides both jail and prison services. These states include Alaska, Connecticut, Delaware, Hawaii, Rhode Island, and Vermont. Some of these states run both jail and prison functions within the same secure facilities, and sometimes the state has separate facilities for its jail and prison populations. In some jurisdictions, the cut-off for serving time in jail instead of prison is 2 years rather than 1 year.
- The U.S. federal government operates several detention centers in major U.S. cities.
State, local, and federal criminal justice systems are full of minutiae, so there will be exceptions to the basics explained here.