Without immigrants US metros will shrink

8220;Immigrants are filling the void as domestic migrants are seeking opportunities in other places,8221; said Mark Mather, a demographer at the Population Reference Bureau, a private research organisation.

For long, immigrants have flocked to major metropolitan areas and helped

them grow.

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 its suburbs, added 1 million immigrants from 2000 to 2006. Without those immigrants, the region would have lost nearly 600,000 people. Without immigration, the sprawling Los Angeles metro area would have lost more than 200,000, the San Francisco, California, 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 taxation records of people moving within the United States and census statistics on immigrants.