The number of foreign-born residents in America was up from 26.4 million in 1999, the report said. About 1 of every 10 persons in America last year was born outside the country.
The estimates released Wednesday were based on an annual survey taken last March by the statistical agency, and were not results from Census 2000. Official Census 2000 numbers on foreign-born residents could be released by the end of this year.
The percentage of immigrants among Americans has increased steadily since 1970, from 4.7 percent to 10.4 percent in 2000, according to the center, a Washington-based think tank that supports stricter controls on immigration.
Mark Mather, an analyst with the Population Reference Bureau, a nonprofit Washington research group, said that states along the coasts and with big urban centers continue to attract the most newcomers to America.
But, "the foreign-born population is increasing everywhere," Mather said. "They are moving out of the coastal areas, but it's a slow process."
About 37 percent of foreign-born residents were naturalized citizens, the Census Bureau said in its report.
More than 30 percent of those naturalized citizens over age 25 had at least a bachelor's degree, compared with more than the roughly 26 percent of native-born Americans over 25 with a college degree. However, only 22 percent of immigrants over 25 without citizenship graduated from college.
Foreign-born residents, regardless of citizenship, were less likely to have a high school diploma: about 87 percent of U.S.-born residents graduated from high school in March 2000, compared wit76 percent of naturalized foreign-born residents, and nearly 60 percent of those without citizenship.
The Census Bureau also found:
The Center for Immigration Studies found that 32.5 percent of U.S. residents born in the Dominican Republic lived in poverty, along with 25.8 percent of residents born in Mexico.
Also, 33.4 percent of all immigrants were without health insurance in March 2000, the center said. That included 57.4 percent of those from El Salvador, and 52.6 percent of those from Mexico.
"On the immigration side, we need to ask whether we want to grow our population this way. I think we don't, so I think we need to do a whole lot more to control illegal immigration," said Steven Camarota, a researcher with the center. "We need to have a policy that selects immigrants on skills and ability to compete rather than a policy that puts all or most of its emphasis on family relationships."