Demography is relentless, we are reminded by a report recently published by the Pew Hispanic Center, noting that the majority of growth among Latinos is now accomplished through births. There are now so many Mexicans residing in this country that they more than replenish their own numbers via their higher fertility.

The Mexican-American Boom: Births Overtake Immigration, Pew Hispanic Center, July 14, 2011

Births have surpassed immigration as the main driver of the dynamic growth in the U.S. Hispanic population. This new trend is especially evident among the largest of all Hispanic groups-Mexican-Americans, according to a new analysis of U.S. Census Bureau data by the Pew Hispanic Center, a project of the Pew Research Center.

In the decade from 2000 to 2010, the Mexican-American population grew by 7.2 million as a result of births and 4.2 million as a result of new immigrant arrivals. This is a change from the previous two decades when the number of new immigrants either matched or exceeded the number of births.

The current surge in births among Mexican-Americans is largely attributable to the immigration wave that has brought more than 10 million immigrants to the United States from Mexico since 1970. Between 2006 and 2010 alone, more than half (53%) of all Mexican-American births were to Mexican immigrant parents. As a group, these immigrants are more likely than U.S.-born Americans to be in their prime child-bearing years. They also have much higher fertility. [. . .]

Read the full 11-page study from Pew here.

Of course the Mexicans had to lay down a substantial base population from which to spawn their growing numbers. And indeed, they have been arriving for several decades, since the disastrous 1965 Immigration Act flung open the doors of immigration permissiveness and extreme diversity. In 1950, for example, there were fewer than half a million Mexicans living in the United States, and now hispanics are the largest minority group.

Open borders allow legal and illegal immigration to have the effect of an invasion, where the home culture is swept away by demanding newcomers who think Americans should learn Spanish.

Interestingly, the Associated Press report begins by saying that "immigration is slowing" - in line with the administration talking point that the illegal immigration crisis is over, so a big Obama amnesty can take place before the next election.

Births, not new immigrants, push US Latino growth, A.P., July 14, 2011

With immigration slowing, babies born in the U.S. rather than newly arrived Mexican immigrants are now driving most of the fast growth in the Latino population.

A new analysis of census data highlights a turning point in Hispanics' rapid U.S. growth. Demographers point to the potential for broader political impact as U.S.-born Mexican-Americans widen their numbers over non-citizen, foreign-born counterparts, who wield no voting rights.

"As these young Latinos age, they will enter public schools, participate in the nation's economy as workers and consumers, and enter the growing pool of Hispanic eligible voters," said Mark Hugo Lopez, associate director of the Pew Hispanic Center, who co-authored the study released Thursday.

The analysis focuses on the growth of Mexican-Americans, who make up more than 60 percent of the U.S. Hispanic population. Tracing a mass Mexican migration to the U.S. that began in 1970 and reached its height during the 1990s, it finds that young Mexicans who crossed the border many years ago are now adding to the population by having many children.

Currently, the median age of Mexican-Americans is 25, compared to 30 for other Hispanic subgroups, 32 for blacks and 41 for whites. Mexican-American women on average will have given birth to 2.5 children by their mid-40s, higher than for other groups.

Meanwhile, immigration from Mexico has fallen off in recent years, dropping by 60 percent since 2006 after a souring U.S. economy and stepped-up border enforcement made it harder and less desirable for undocumented workers to enter the country. As a result, the number of new immigrants from Mexico declined over the last decade to 4.2 million, from 4.7 million in 1990-2000.

In all, the Mexican-American population grew by 11.4 million over the last decade, of which 63 percent came as a result of births. That is a reversal from the previous two decades, when the number of new Mexican immigrants either matched or exceeded the number of Mexican births.

Among Hispanics as a whole, about 58 percent of the population increase since 2000 were a result of births.

The numbers come as Hispanic groups are seeking more political influence. States are currently redrawing their political maps based on population and racial and ethnic makeup. Now representing 16 percent of the U.S. population, Hispanics added more than 15 million people over the last decade and accounted for more than half of the nation's total population increase.

Still, their voting power has not always matched their numbers, partly because a disproportionate share of U.S. Hispanics are either children or non-citizens. Just 42 percent of all Hispanics in the U.S. are eligible to vote, compared to 78 percent for whites and 66 percent for blacks.

Currently more than 60 percent of all Hispanics are U.S.-born, many of them children.

Lopez says that is now changing, with some 600,000 young Hispanics who were born in the U.S. turning 18 each year to enter a widening pool of more than 21 million Hispanic eligible voters.

Other findings: _About 6.5 million, or more than half of all Mexican immigrants, were in the U.S. illegally last year. Many of these illegal immigrants gave birth to children in the U.S.; about 68 percent of the 350,000 U.S. births to illegal immigrants last year were to Mexican parents.

_Birth rates differ by immigration status: on average, a Mexican immigrant woman in her 40s has 2.7 children, compared to 2.1 for a U.S.-born Mexican-American.

_About 1 in 10 of all native-born Mexicans opt to migrate to the U.S., seeking jobs and a better life. Among native-born Mexicans in their prime working ages of 30 to 44, the share is even higher: about 1 in 5 men, and more than 1 in 7 women migrate to the U.S.

The Pew analysis is based on 2010 census surveys from the U.S. and Mexico. Because the U.S. Census Bureau does not ask people about their immigration status, estimates on illegal immigrants are derived largely by subtracting the estimated legal immigrant population from the total foreign-born population.