Interest in leaving Mexico to immigrate to the United States is the lowest it's been since 1950, according to recent research from Princeton University.

"No one wants to hear it, but the flow (of illegal traffic) has already stopped," said Douglas S. Massey, co-director of the Mexican Migration Project at Princeton, an extensive, long-term survey in Mexican emigration hubs. "For the first time in 60 years, the net traffic has gone to zero and is probably a little bit negative."

Fewer Mexicans entered the United States last year than left, according to the nonpartisan Pew Center. The number of Mexican immigrants living in the United States without papers dropped from a high of 7 million in 2007 to 6.5 million in 2010. Illegal border crossings and visa violations dropped from a 2004 high of 525,000 to just 100,000.

"I don't think anybody would have predicted the kind of fall-off we've had," Wayne Cornelius, co-director of the University of California's Center on Migration and Health, told The San Diego Union-Tribune. "We didn't anticipate this sharpest economic contraction. We are in uncharted waters."

Demographers interviewed by The San Diego Union-Tribune attributed the trend to The Great Recession and increased U.S. border enforcement. A recent New York Times investigation, though, suggested the reasons may be more Mexico-centric.

Here are few trends that may be motivating Mexicans to stay home (read the full New York Times article here):

Mexican families are getting smaller. In 1970, the fertility rate was about 7 children per woman. Now, it is about 2. The country's pool of job seekers has shrunk accordingly. About 1 million Mexicans entered the job market annually during the 1990s. Since 2007, that number has fallen to an average of 800,000. By 2030, it's expected the country will contribute only 300,000 new workers per year.

Employment opportunities in Mexico are expanding. While wages in the United States fell, wages in Mexico rose. At one time, a migrant worker could make 10 times as much abroad as at home. Now the ratio is closer to 4:1, according to research by David Fitzgerald, a migration expert at the University of California, San Diego.

Quality of life in Mexico has improved. Running water, electricity and trash collection — once unheard of in rural districts — is now available to 90 percent of Jalisco's homes, according to government figures. The percentage of people living in homes with dirt floors dropped from 12 percent in 1990 to just 3 percent in 2010.

More Mexicans are getting an education. The number of senior high schools or preparatory schools has more than doubled in some parts of the country, according to census data. About half of the students living in Jalisco now move on to college, compared to 30 percent in 2001. The number of professional degree holders in the poor southern states of Chiapas and Oaxaca rose from 244,322 to 525,874 in 2010. "They're identifying more with Mexico," Agustín Martínez González, a teacher, told the New York Times. "With more education, they're more likely to accept reality here and try to make it better."

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