The latest figures on US prisons show a population equivalent to that of a large city is in jail. "At mid-year 1998 the nation's prisons and jails incarcerated an estimated 1,802,496 persons," said the survey from the US Justice Department.
"It is unique in a democratic society," said Mark Mauer of the Sentencing Project, a group which questions American judicial policy.
That figure represents a rate of incarceration of 668 inmates per 100,000 residents, a doubling since 1985. By contrast, in England and Wales - which have one of the highest rates of incarceration in Europe - the figure is around 120 per 100,000. Only Russia, at 685 per 100,000, has a higher proportion of the population in jail, and the US may overtake it. The total cost of the US prison programme is about $40bn (pounds 25bn).
The staggering increase in the US prison population over the past 20 years has come about because of mandatory minimum sentences, the policy of "three strikes and you're out", and "truth in sentencing", which mean that inmates serve more of their sentences and are less likely to get parole.
The prison population has slowed its rate of growth as the crime rate falls in the US to 30-year lows, but it still increased by 4.4 per cent from 1997 to 1998, the survey showed.
The number of prisoners first hit a million in 1990, and even though the increase has slowed it seems set to hit 2 million within two years. Nearly 90 per cent of prisoners are men, but the adult female prison population is growing faster than the male.
The prison system is filled over capacity, and it is adding more prison beds every two years than there are prisoners in total in Britain.
The prison population is disproportionately black and Hispanic.
"Relative to their number of US residents, black non-Hispanics were six times more likely than white non-Hispanics, nearly two times as likely as Hispanics, and almost 7.5 times more likely than persons of other races to have been held in a local jail on 30 June1998," the Justice Department stated.
A growing proportion of prisoners are doing time for drugs offences, but there are some anomalies in sentencing. The penalties for crack cocaine, a cheap but powerful high, are significantly harsher than those for powder cocaine, which is largely the preserve of the middle-class drug abuser.
The prison population is so large that it distorts US unemployment figures and skews the voting register.
The Sentencing Project says that nearly 4 million Americans are denied the right to vote because they have a felony conviction, and nearly 1.4 million of them are black males.
The highest rates of incarceration are in the neighbouring southern states Texas, Louisiana, Oklahoma and Mississippi. Texas and Louisiana both have more than 700 per 100,000 of their populations in jail, well over the Russian figure.Reuse content