The number of inmates in adult correctional facilities in the United States has topped two million for the first time, the Census Bureau said yesterday. But in a reversal from 2000, more Americans over all now live in college dormitories than in prisons.

In a detailed look at people living in what the bureau calls group quarters, the census counted 2.3 million Americans in college and university dormitories, 2.1 million in adult correctional institutions and 1.8 million in nursing homes.

The number of state and federal prisoners in 2006 was more than double the prison population in 1990 and up slightly from nearly 2 million in 2000. Women accounted for 10 percent of the inmates in 2006, compared with 8 percent in 1990.

In 2000, the last year that the census measured people in group quarters, inmates in adult and juvenile correctional institutions slightly outnumbered dormitory dwellers at colleges and universities.

According to government figures, more than twice as many young black men are now attending college than are imprisoned.

A number of studies, including one by the Justice Policy Institute, which advocates alternatives to incarceration, have pointed out that over all, more black men are in prison than are enrolled in colleges and universities.

But among 18- to 24-year-olds, while black male prisoners outnumber black men living in college dorms, more young black men are enrolled in college (and live either on campus or elsewhere) than are incarcerated.

In 2003, according to Justice Department figures, 193,000 black college-age men were in prison. While 132,000 black college-age men were living on campus, an additional 400,000 or so were attending college but living someplace else.

Among all 18- to 24-year-old men and women, according to an analysis by Andrew A. Beveridge, a demographer at Queens College of the City University of New York, 93 percent more whites, 40 percent more Hispanics and 29 percent more blacks were living in dormitories than in prisons.

The Census Bureau’s 2006 American Community Survey found other wide disparities on the basis of race and ethnicity.

Among people living in group quarters, whites were almost twice as likely to be living in a dormitory than a prison, while Asians were nine times more likely to be in a college dorm than in prison.

But blacks and Hispanics were about three times as likely to be imprisoned than to be living in a dormitory.

Put another way, about 46 percent of the prison population constituted whites who are not Hispanic, 41 percent were black, comprising Hispanic and non-Hispanic, and 19 percent identified themselves as Hispanic. Since 2000, the proportion of the prison population made up of whites and blacks had declined slightly; the share of Hispanics increased.

Among immigrants living in group quarters, Europeans were more likely to be in nursing homes, Asians in dormitories and Latin Americans in correctional facilities.

In contrast to the prison population, residents of nursing homes were disproportionately women (nearly 70 percent, down slightly from 2000) and white (84 percent).

Blacks accounted for 13 percent, about their share of the total population. Almost three-quarters were 75 and older; their median age was 83.2.

Copyright 2007 The New York Times Company. Reprinted from The New York Times, National, of Thursday, September 27, 2007.