More than one in 100 adults are now behind bars in the US, home to the world's largest penal population, with a startling one in nine young black men incarcerated, a study showed on Thursday.
The prison and jail population rose by 25,000 to 2.3 million last year, out of a US adult population of 230 million, bringing the incarceration rate to one in 99.1 for the first time in US history, the Pew Center on the States said.
By comparison, China, with a population of 1 billion people, was second in the world with 1.5 million inmates, followed by Russia with 890,000 people in the slammer, the study said.
The US also has the dubious distinction of leading the planet in the rate of incarceration, which is higher than nations like South Africa and Iran, the study said.
By comparison, in Germany, 93 people are in prison for every 100,000 people, including minors, the Washington-based independent research group said. The rate is about eight times higher in the US: 750 per 100,000.
The statistics are particularly striking among minorities.
While one in 106 adult white men are incarcerated, one in 36 Hispanics and one in 15 black Americans are behind bars, according to Pew's examination of Justice Department data from 2006. Younger black men fare even worse, with one in nine black Americans ages 20 to 34 held in cells.
While men are still 10 times more likely to be incarcerated than women, the female penal population is "burgeoning at a far brisker pace," the study said.
One in 265 women ages 35 to 39 are behind bars, but minority women are also sent to jail or prison at a higher rate than white women.
One in 100 black women and one in 297 Hispanic women are incarcerated, compared with one in 355 white women, the study said.
Tough policies, such as "three strikes" laws boosting prison time for repeat offenders, have mainly fueled the rise in the penal population, rather than an explosion in crime or overall population, it said.
Despite the rising prison population, the national recidivism rate has virtually stood still, with about half of released inmates returning to jail or prison within three years, Pew said.
Moreover, the prison growth is putting budgetary pressure on state governments, forcing them to make tough choices about spending, the study said.
"For all the money spent on corrections today, there hasn't been a clear and convincing return for public safety," Adam Gelb, director of Pew's Public Safety Performance Project, said in a statement.
Two decades ago, the 50 US states spent US$10.6 billion from their general funds -- their primary discretionary money -- on corrections. Last year, they shelled out US$44 billion, or 315 percent more than 20 years ago.
The study found that over the same 20-year period, spending for corrections jumped 127 percent compared with a 21 percent rise for higher education.
The economic strain has led states to change their policies and find other ways to keep low-risk offenders out of trouble, including through day reporting centers, treatment facilities, electronic monitoring systems and community service, it said.
"Some state policymakers are experimenting with a range of community punishments that are as effective as incarceration in protecting public safety and allow states to put the brakes on prison growth," said Susan Urahn, managing director of the Pew Center on the States.