Births have overtaken immigration as the driving force behind the growth of the Mexican-American population in the United States in the past decade, according to a report released Thursday by the Pew Hispanic Center.
The same can be said for the entire Hispanic population of the United States, which grew from 35.3 million in 2000 to 50.5Â million in 2010, accounting for 16.3% of the U.S. population, according to U.S. Census Bureau data. About 58% of that growth resulted from births rather than the arrival of new immigrants, the report says.
The trend is most evident among Mexican-Americans, whose numbers grew by 7.2 million as a result of births and 4.2 million from new immigrant arrivals in the past decade, reversing trends from the previous two decades, when the number of new immigrants matched or exceeded the number of births, the report says.
Mexican-Americans are the nation's largest Hispanic group, Â at around 31.8 million, or 63% of the U.S. Hispanic population and 10% of the total U.S. population.
In the Pew report, the term Mexican-American applies to people of Mexican origin, regardless of immigration status. The study noted that in 2010, 52% of people of Mexican origin were in the U.S. illegally, and that 68% of births to undocumented aliens were to Mexican nationals.
What's behind the change?
Mexican-Americans are more likely than U.S.-born Americans to be in their prime child-bearing years, and they also have higher fertility rates, the report says. Another significant factor is a steep decline in Mexican immigration to the United States in recent years.
Hispanic births accounted for 25% of the nationâ€™s newborns in 2008, the report says, citing statistics from the Centers for Disease Control. U.S. births are also disproportionately Mexican-American. While 10% of the nationâ€™s population in 2008 was Mexican-American, 16% of the nationâ€™s births were to Mexican-American mothers.
Meanwhile, the number of new immigrants arriving from Mexico fell by 60% between 2006 and 2010 because of declining job opportunities in the U.S., increased border enforcement and economic growth in Mexico, the report says, citing a previous Pew Hispanic Center study of Mexican immigration trends.
Age and fertility explain the high share of births among Mexican-Americans, the report says. On average, Mexican-Americans are younger than other major racial and ethnic groups, with a median age of 25, compared with 30 for non-Mexican-origin Hispanics and 41 for whites.
Mexican-American women also have more children than their counterparts in other racial and Hispanic origin groups. The typical Mexican-American woman between 40 and 44 has given birth to 2.5 children, compared with 2.3 children for the typical same-aged Hispanic woman and 1.8 children for the typical same-aged white woman, according to Pew Hispanic Center tabulations from the 2006 to 2010 June Fertility Supplements of the U.S. Current Population Survey.
The Hispanic share of the population is projected to rise from 16.3% in 2010 to 29% by the middle of this century, with the bulk of the future increase driven by births rather than the arrival of new immigrants, the report says.