The number of people in jail in the United States rose to more than two million for the first time ever last year, the government has said.
Jails now hold nearly twice as many inmates as in 1990
Official figures show the US has the biggest prison population in the world, and the highest number of inmates as a proportion of its population.
A report from the US Justice Department also estimated 12 per cent of black men in their 20s and early 30s were in jail last year.
Just 1.6 per cent of white males in the same age group were locked up.
The overall increase - almost double the number in 1990 - has been pushed up by a "get tough" sentencing policy that has led to longer sentences for drug offenders and other criminals.
According to the report, the 50 US states along with the District of Columbia and the federal government held as many as 1,355,748 people as of June last year.
"Get tough" sentencing has increased the prison population
Another 665,475 inmates were under lock and key in municipal and local jails.
In total, one in every 142 people living in the United States was in jail last year.
That figure would be higher if inmates handled by the US Immigration and Naturalization Service, and others from institutions such as military jails were included.
The US currently incarcerates more people than any other country in the world.
In China, which has a population of about 1.3 billion, there are more than 1.4 million inmates, according to Britain's Home Office. The US has a population of 286 million.
Russia, which has a population of 144 million, has a prison
population of about 920,000.