The national debate over the plight of people without health insurance directly affects an unusually small portion of Pittsburgh's population, as new data show it is among the best-insured parts of the country.

Of the 25 largest metropolitan areas, Pittsburgh trails only Boston in its share of people with health insurance coverage. Nearly 92 percent of people of all ages in the seven-county region have public or private insurance, compared to less than 85 percent nationally, according to data released yesterday by the U.S. Census Bureau.

The health insurance information is among wide-ranging topics covered by the bureau's 2008 American Community Survey, a sampling of 3 million households. The annual survey replaces the census long form that formerly accompanied the national head count every 10 years.

The survey provided insurance-coverage estimates for the first time for the nation's cities and counties above 65,000 in population. Analysts offered several reasons why Pittsburgh fares well in rankings:

• Nearly all people over 65 have Medicare coverage, and Pittsburgh has a larger proportion of that age group than elsewhere: 17.1 percent in the metropolitan area compared to 12.8 percent for the nation.

• Pennsylvania's CHIP program provides widespread insurance coverage for children who might not have it among low-to-moderate income households in other states. In the Pittsburgh region, all but 3.9 percent of those under age 18 are insured, compared to a national uninsurance rate of 9.9 percent for children.

• The Pittsburgh area's economy has endured the recession better than other parts of the country, and the strong history of industrial unionization and high percentage of jobs in education and health care all make it more likely that working people here are insured. Among those ages 18 to 64, 88.4 percent here are insured, compared to 80.2 percent nationally.

All of that means Pittsburgh is outpaced only by the largest city in Massachusetts, a state that has implemented its own form of universal health coverage. More than 95 percent of Bostonians are insured.

Cities ranking low in health insurance coverage, such as Houston, Dallas and Miami, have large immigrant populations in common, and those individuals are less likely to be covered.

"If you think about the populations who are likely to have coverage, and our high proportion of elderly, and the very high-risk populations we don't have, it makes sense that we would be at the top," said Judith Lave, a University of Pittsburgh professor of health economics, though she was surprised to learn that Pittsburgh trailed only Boston.

Meanwhile, those who work with low-income populations locally said the figures do not negate the growing number of people in need, due to job cutbacks.

"As more plants close, there's more people uninsured," said Tony Lodico, co-coordinator of the Mon Valley Unemployed Committee. "There's often middle-aged workers involved, and they greatly fear losing what they've been able to accumulate. ... You could lose it all in one illness."

Other than health insurance, the American Community Survey highlighted other ways in which the region differs from national norms:

• The Hispanic population continues to be estimated at just 1.1 percent in metropolitan Pittsburgh, while it grew nationally from 15.1 percent to 15.4 percent between 2007 and 2008.

• The percentage of U.S.-born population is estimated at 97 percent locally, compared to 87.5 percent nationally.

• Just 1.4 percent of the region's residents identify themselves as belonging to two or more races, while 2.3 percent do so nationally.

• The proportion of the population ages 85 or older around Pittsburgh is 2.8 percent, compared to just 1.8 percent nationally.

• The average household size fell slightly locally, from 2.34 to 2.31 between 2007 and 2008, while it grew nationally from 2.61 to 2.62.

• An estimated 8.5 percent of Pittsburgh-area men and 9.9 percent of women are presently divorced, significantly lower than national rates of 9.4 percent for men and 11.9 percent for women.

• The percentage of military veterans among both the local and national populations keeps declining, but they stand at 11.3 percent locally compared to 9.8 percent nationally.

More information is available at www.census.gov, by clicking on American Community Survey at the top of the page.