PHOENIX (Reuters) - For the first time births have overtaken immigration as the main driver of dynamic growth in the U.S. Hispanic population, according to a new study released on Thursday.
The Pew Hispanic Center survey found the new trend especially evident among Mexican-Americans, who account for almost two thirds of the U.S. Latino population.
Analysts said the study showed that the U.S. Latino population would continue to grow despite efforts to close the porous border with Mexico and stem illegal immigration, but that the trend would also likely lead to a diversification of Latinos, both culturally and politically.
The study, which drew on U.S. Census Bureau data and other government sources, noted the Mexican-American population grew by 7.2 million as a result of births in the decade to 2010, while new immigrants added 4.2 million people.
"For Mexican-Americans, births were more important for their population growth during the decade than immigration," said Mark Lopez, an associate director of the Pew Hispanic Center and a co-author of the report.
"That's actually a departure from what we saw in the previous two decades," he added.
The study found growth in the Mexican-American population in the 1990s was split equally between births and new immigration, which each added 4.7 million people.
A decade earlier in the 1980s, by contrast, the Mexican-American population gained 3.1 million people through new immigration, while births added another 2.7 million.
"You could close the border completely to anyone from abroad, and the Hispanic population is going to continue to comprise a larger and larger share of the U.S. population for the next 50 to 100 years," Mark Jones, a political scientist at Rice University in Texas, told Reuters.
Bruce Merrill, a emeritus political scientist and pollster at Arizona State University, said the shift highlighted by the report showed "the potential for the Hispanic community to become more diverse within itself."
Whereas Hispanics voted by a two-to-one margin to elect Democrat Barack Obama president over Republican rival John McCain in 2008, those born in the United States tend to be more conservative in their outlook, he said.
"The people coming in as opposed to the people who are born here tend to be a different kind of person politically," Merrill said, noting that U.S.-born Hispanics more often supported tougher enforcement on the southwest border with Mexico.
"When you look at the Hispanics who are in the country legally, they tend to be very supportive of pretty strong means of supporting the border," Merrill said.
The study found the surge in births among Mexican-Americans was largely down to the immigration wave that has brought more than 10 million immigrants to the United States from Mexico since 1970.
Hispanics are the largest and fastest growing minority in the United States, totaling 50.5 million in 2010, according to the U.S. Census Bureau. Mexican-Americans comprised 63 percent of that total.
A previous Census Bureau projection forecast ethnic and racial minorities in the United States to become the majority by 2050, by which time nearly one in three U.S. residents will be Latino.
Reporting by Tim Gaynor; Editing by Jerry Norton and Mohammad Zargham