http://www.nytimes.com/interactive/2011/07/06/world/americas/immigration.html?hp
Economic, demographic and social changes in Mexico are suppressing illegal immigration as much as the poor economy or legal crackdowns in the United States.
The extraordinary Mexican migration that delivered millions of illegal immigrants to the United States over the past 30 years has sputtered to a trickle, and
research points to a surprising cause: unheralded changes in Mexico that have made staying home more attractive.
A growing body of evidence suggests that a mix of developments expanding economic and educational opportunities, rising border crime and shrinking families are suppressing illegal traffic as much as economic slowdowns or immigrant crackdowns in the United States.
Mexican immigration has always been defined by both the push (from Mexico) and the pull (of the United States). The decision to leave home involves a comparison, a wrenching cost-benefit analysis, and just as a Mexican baby boom and economic crises kicked off the emigration waves in the 1980s and 90s, research now shows that the easing of demographic and economic pressures is helping keep departures in check.
In simple terms, Mexican families are smaller than they had once been. The pool of likely migrants is shrinking. Despite the dominance of the Roman Catholic Church in Mexico, birth control efforts have pushed down the fertility rate to about 2 children per woman from 6.8 in 1970, according to government figures. So while Mexico added about one million new potential job seekers annually in the 1990s, since 2007 that figure has fallen to an average of 800,000, according to government birth records. By 2030, it is expected to drop to 300,000.