The U.S. population will soar to 438 million by 2050 and the Hispanic population will triple, according to projections released Monday by the Pew Research Center.
The latest projections by the non-partisan research group are higher than government estimates to date and paint a portrait of an America dramatically different from today's.

The projected growth in the U.S. population — 303 million today — will be driven primarily by immigration among all groups except the elderly.

"We're assuming that the rate of immigration will stay roughly constant," says Jeffrey Passel, co-author of the report.

Even if immigration is limited, Hispanics' share of the population will increase because they have higher birth rates than the overall population. That's largely because Hispanic immigrants are younger than the nation's aging baby boom population. By 2030, all 79 million boomers will be at least 65 and the elderly will grow faster than any other age group
http://www.usatoday.com/news/nation/2008-02-11-population-study_N.htm