One in every 11 people born in Mexico is now living in the United States, according to a a study of immigration trends by the Pew Hispanic Center (search). That's 10.5 million Mexicans, more than half of whom are here illegally.

“The situation is simply out of control,” said immigration activist Ira Mehlman, of the Federation for Immigration Reform.

Illegal immigrants, whom this study refers to as "unauthorized migrants," are pushing down the quality of schools and pushing up crime rates and health care costs, the study says. Because they primarily work low-wage jobs, Mehlman says they're pushing out the middle class and creating a Third World subculture within the United States (search).

“We're destroying what we have in this country,” Mehlman said. “We're obliterating the future for our children and we're doing it for the sake of a few employers who want low-wage labor.”

Latino labor leaders say Mexicans are coming north looking for better lives and that low-wage jobs here are better than no jobs there. Besides, they ask, if immigrants don't take those jobs, who will?

“You go to any part of California and the Southwest — now I'm traveling through the southern states through the Midwest — and you see who's working in the fields, who's picking the crops,” said union leader Maria Elena Durazo. “It's Mexican immigrants.”

Durazo also believes immigrants, legal and otherwise, are not lowering wages but boosting productivity.

The contribution of Mexican immigrants has been extremely important to the U.S. economy.

Said Mehlman: “It's absolutely impossible to try and build a flourishing, competitive economy when a growing portion of the labor force is simply illiterate.”

Over the past 10 years illegal immigration has surpassed legal immigration into the United States, and there's no end in sight. By many estimates the number of Mexican immigrants, legal and illegal, could double in the next 15 years.

Click in the video box above to watch a report by FOX News’ Trace Gallagher.