Data indicates that more immigrants are moving from the United States to Mexico than are moving from Mexico to the US.

From 2009 to 2014, 1 million Mexicans, including their American-born children, left the US for Mexico, according to the 2014 Mexican National Survey of Demographic Dynamics, cited by the Pew Research Center.

The trend is an increasingly significant phenomenon that has started to affect Mexico's economy and culture.

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In a twist to the decades-long trend of Mexican immigrants journeying to the United States, data indicates that in recent years, more people have done the opposite, moving from the US to its southern neighbor in droves.

From 2009 to 2014, 1 million Mexicans, including their American-born children, left the US for Mexico, according to the 2014 Mexican National Survey of Demographic Dynamics, cited by the Pew Research Center.

US census data also shows that in that same period, 870,000 Mexicans migrated to the United States, Pew said.

In May, Mexico's statistics institute estimated that there were at least 799,000 US-born people living in Mexico — that's four times as many as in 1990 and probably an underestimate, according to The Washington Post.

Why Mexicans are returning home and why Americans are going with them

A man walking on the Mexican side of the US-Mexico border. Getty Images/Mario Tama

There are a couple of reasons that more people are returning to Mexico than are migrating to the United States, but the main one is the US economy's slow recovery from the 2008 financial crisis, according to Pew.

Read more: The Trump administration's tough border policies could be worsening a thriving black market of smugglers that's only growing more sophisticated, experts say

Beyond that, Mexicans have an increasingly optimistic view of their lives south of the US-Mexico border.

A 2015 Pew survey found that 48% of Mexican adults said they believe life is better in the US, and 33% said they believe it is neither better nor worse than life in Mexico — 10 percentage points higher than in a 2007 survey.

The migration trend has affected life in Mexico, with American immigrants helping to boost local Mexican economies and transform neighborhoods and schools, The Post reported.

"It's beginning to become a very important cultural phenomenon," the Mexican foreign minister, Marcelo Ebrard, told The Post. "Like the Mexican community in the United States."

Most Americans living in Mexico are unauthorized immigrants

Mexico City. Anton_Ivanov/Shutterstock

A 2015 study from Mexico's National Institute of Statistics and Geography found that the vast majority of Americans living in Mexico were unauthorized immigrants or had errors with their paperwork.

But unlike the Trump administration, which has vowed to crack down on illegal immigration and deport those who don't have valid visas or green cards, the Mexican government has largely shrugged off the issue.

"We have never pressured them to have their documents in order," Ebrard told The Post.