Many smaller areas, including Battle Creek, Mich., Ames, Iowa, and Corvallis, Ore., would shrink as well, according to population estimates to be released Thursday by the Census Bureau.
"Immigrants are filling the void as domestic migrants are seeking opportunities in other places," said Mark Mather, a demographer at the Population Reference Bureau, a private research organization.
Immigrants long have flocked to major metropolitan areas and helped them grow. But increasingly, native-born Americans are moving from those areas and leaving immigrants to provide the only source of growth.
The New York metro area, which includes the suburbs, added 1 million immigrants from 2000 to 2006. Without those immigrants, the region would have lost nearly 600,000 people.
Without immigration, the Los Angeles metro area would have lost more than 200,000, the San Francisco area would have lost 188,000 and the Boston area would have lost 101,000.
The Census Bureau estimates annual population totals as of July 1, using local records of births and deaths, Internal Revenue Service records of people moving within the United States and census statistics on immigrants. The estimates released Thursday were for metropolitan areas, which generally include cities and their surrounding suburbs.
Among the findings:
The White House floated a plan last month that would grant work visas to illegal immigrants, but they would have to return home and pay hefty fines to become legal U.S. residents.
Lawmakers were unable to reach an agreement last year on how best to stem the flow of illegal immigrants. Immigration was a contentious issue in many congressional races in November.
In the decade ending last year, 10.7 million people who didn't have Social Security numbers — most of them immigrants — paid more than $50 billion in income taxes, reports CBS News correspondent Sandra Hughes.
The growing immigrant population is also expected to help cushion the economic blow when baby bombers retire, Hughes reports, and immigrants are the ones who will be caring for many aging and ailing boomers.
But many demographers associate shrinking populations with economic problems, typically poor job markets or prohibitive housing prices.
Legal and illegal immigration is costing the nation billions of dollars each year, reports CBS News correspondent Sharyn Alfonsi. The price tag includes $1.6 billion for the prison system, $1.9 billion for food assistance programs and $1.5 billion for federal aid to schools.
"A lot of cities rely on immigration to prop up their housing market and prop up their economies," said William Frey, a demographer at the Brookings Institution, a Washington think tank.
Advocates for stricter immigration laws question whether a stable, or even a shrinking population, is bad.
"Don't we have concerns about congestion and sprawl and pollution?" asked Steven A. Camarota, director of research at the Center for Immigration Studies, which advocates for stricter immigration policies.
"Maybe those metro areas should think about what it would take to make Americans want to live there," Camarota said.