prison, place of confinement for the punishment and rehabilitation of criminals. By the end of the 18th cent. imprisonment was the chief mode of punishment for all but capital crimes. At that time, largely as a result of the writings of Cesare Beccaria in Italy and John Howard and others in England, there was a wave of penal reform and improvement in conditions. The earliest North American reform centered in Philadelphia (1790) and in Auburn, N.Y., where systems of solitary confinement and congregate labor were introduced. These penitentiaries required the prisoners to maintain absolute silence. Reform efforts continued through the 19th cent., with two notable women (Elizabeth Fry and Dorothea Dix) among the reformers. British and Irish influences led to the practice of parole.

In the 20th cent. efforts were made in the United States to eliminate unsanitary and demoralizing prison conditions. Reforms included the individualization of treatment, psychiatric assistance, constructive labor and vocational training (see convict labor), professionalization of correctional officers, and the introduction of work release programs. In some places, however, corporal punishment is still used. Until the late 1970s, there was a growing tendency to regard the basic aim of imprisonment as rehabilitation of the criminal rather than as punishment or protection of society. That trend, however, has been reversed. Correspondingly the length of sentences has been extended, and the number of inmates increased substantially. From 1980 to 1990, the nation's federal and state prison population increased by 134% to 771,243 persons; by 2000 it was 1,381,892 persons, a 79% increase from 1990. From 1970 to 2000 the number of state inmates alone increased 500%. By 2005 the growth of the prison population appeared to be growing more slowly; some 1,446,269 persons were in federal and state prisons, only a 4.6% increase from 2000, due mainly to a slowing in the growth of the state prison population. An additional 874,090 persons were in local jails and other facilities; the local inmate population increased by 20% from 2000 to 2005. The increase in the number of inmates contributed to a fall in the crime rate, but increased sentences and other penalties appear not to have acted as a deterrent to crime among released inmates, who have become slightly more likely to be rearrested on average.

The chief types of prisons in the United States (with similar institutions in other countries) are the local jail, for pretrial detention and short sentences, and the state and federal penitentiaries, for convicts with long sentences. Special penal institutions are provided for juveniles, the sick, and the criminally insane. The rapid increase in prison population has led some U.S. jurisdictions to explore letting private contractors operate prisons. These private prisons increased from one or two in the mid-1980s to more than 150 by the end of the century. Some of these institutions proved problematic, often because they were not subject to government regulation or because they took in out-of-state prisoners. Juvenile delinquents are usually sent to reformatories or other correctional institutions. In the face of growing U.S. youth crime from the 1970s to the 90s, military-style "boot camps" for juvenile offenders were widely instituted. Many of these were subsequently criticized for brutality and high recidivist rates, and some were scaled back or closed. Among famous prisons in history are the Bastille in Paris and the Tower of London. In the United States, Sing Sing (see Ossining) and Alcatraz (now closed) are the two best known.

Libby Prison, in Richmond, Va., a Confederate prison for captured Union officers in the American Civil War. It was previously a tobacco warehouse. Living conditions were extremely bad; the food, sometimes lacking altogether, was poor and sanitation practically nonexistent. Thousands died there. Except for Andersonville Prison, Ga., Libby Prison was the most notorious in the Confederacy.

Fleet Prison, former jail in London, England. Rebuilt after it was destroyed in the Peasants' Revolt of 1381, again after the great fire of 1666, and once more after the Gordon riots of 1780, it was finally demolished in 1845-46. After the 17th cent. it was notable as a debtors' prison. Fleet marriages were clandestine and irregular ceremonies performed at Fleet Prison by debtor clergymen. Although not illegal, the system was so abused that it was abolished in the reign of George II.

Dartmoor Prison, English prison, at Princetown, Devonshire, built (1806-9) to house French captives during the Napoleonic Wars. During the War of 1812 many American prisoners were confined there, and their brutal mistreatment was investigated after the war by an Anglo-American commission that awarded compensation to the families of those who had died there. Between 1812 and 1816 about 1,500 American and French prisoners died in the prison and were buried in a field beyond the prison walls. Unoccupied for over 30 years, Dartmoor was reopened in 1850 as a civilian prison for convicts sentenced to long terms of imprisonment or to hard labor.

Institution for the confinement of people convicted of crimes. Prisons are administered by state, provincial, or national governments and house inmates for relatively long terms. They thus differ from jails, which usually are under local jurisidiction and house inmates serving short sentences. Until the late 18th century, prisons were used mainly for the confinement of debtors who could not meet their obligations, of accused persons waiting to be tried, and of convicts who were waiting for their sentences of death or banishment to be put into effect. Later, imprisonment itself came to be accepted as a means of punishing convicted criminals. In early U.S. prisons, prisoners were kept in isolation; in the 19th century, they were permitted to work together, but only in silence. At the end of the 19th century, prison reformers successfully advocated segregation of criminals by type of crime, age, and sex; rewards for good behaviour; indeterminate sentencing; vocational training; and parole. In the late 20th century, prison populations in many countries began to explode as arrests for violent offenses and for possession of small amounts of illegal drugs increased.

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