One In 100 US Adults Behind Bars

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 time higher in the United States: 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 African-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 African-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 to 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 goverments, 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 10.6 billion dollars from their general funds -- their primary discretionary money -- on corrections. In 2007, they shelled out 44 billion dollars, 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 to a 21 percent rise for higher education.