According to this story in the New York Times, the United States prison population grew by 25,000 last year, bringing it to almost 1.6 million. Another 723,000 people are in local jails.
The number of American adults is about 230 million, meaning that one in every 99.1 adults is behind bars.
Incarceration rates are even higher for some groups. One in 36 Hispanic adults is behind bars, based on Justice Department figures for 2006. One in 15 black adults is, too, as is one in nine black men between the ages of 20 and 34.
The report, from the Pew Center on the States, also found that only one in 355 white women between the ages of 35 and 39 are behind bars but that one in 100 black women are.