Undocumented immigration into the United States dropped sharply during the Great Recession and continued to decline through 2014, according to a Pew Research Center estimate released this week.

The decreased influx of newcomers primarily came from Asian, Central American, and African countries, not Mexico, the neighbor nation commonly attributed to the nation's immigrant population. Mexicans led the way in the 1990s and early parts of the 2000s but fewer jobs, enhanced border enforcement, increased deportation efforts from the Obama administration discouraged them from crossing over.

Since 2009, more undocumented Mexicans have left the U.S. than entered.

"As overall net immigration from Mexico declined, immigration from Asia did not flag - indeed, it somewhat increased," Pew researchers wrote. "As a result, among all newly arriving immigrants to the U.S., more now come from Asia than from Latin America, a change since 2008."

Pew estimated 350,000 immigrants arrive each year, only about 100,000 of which come from Mexico; about 5.8 million undocumented Mexicans live in the U.S. two years ago, down 57 percent from 2007. Arrivals from Asia and Central America reached 5.3 million the same year, a 325,000 increase since 2009.

Temporary Protections and Overstayed Visas

While Mexicans are finding reason to leave the U.S., more and more from Honduras, El Salvador, and Guatemala see it as their only chance of survival.

Immigrants from countries designated for Temporary Protection Status can stay if they are escaping civil war or immediate natural disasters. During fiscal year 2014, nearly 70,000 unaccompanied children were caught along the U.S.-Mexico border. They fled Central America in fear of gang violence, sexual violence, and poverty, prompting a debate whether they warrant TPS.

The second-biggest influx comes from East Asian countries like China, the birthplace of some 1.4 million undocumented individuals in the U.S in 2014. They arrive with legal status but overstay visas.

As for the other incoming arrivals, Pew researchers found the following: 650,000 came from South America, 425,000 from the Caribbean, and 600,000 from Canada and Europe each.

Despite anti-immigration rhetoric spilled during the 2016 presidential election, the Middle Eastern immigration population is relatively small. Undocumented immigrants from Islamic nations accounted for 140,000 arrivals in 2014, or about one percent of the total.

Where Undocumented Immigrants Live

The rise of undocumented populations in six states coincides with the fall in seven others. Massachusetts, New Jersey, Pennsylvania, Virginia, and Washington saw increases in immigration coming from nations other than Mexico. The Mexican population in Louisiana grew while the rest of the population stabilized.

Declines in Alabama, California, Georgia, Illinois, Kansas, Nevada, and South Carolina were directly influenced by Mexicans.

"Mexico is the leading birth country of unauthorized immigrants in at least 38 of the states and District of Columbia," the report read. "A variety of other countries dominate the unauthorized immigration population in other states."

"El Salvador is the leading birth country in the District of Columbia, Maryland and Virginia. The Philippines is the top birth country in Alaska and Hawaii. Other top birth countries include Brazil in Massachusetts, India in New Hampshire and Guatemala in Rhode Island."

In 1990, 80 percent of the undocumented immigrant population lived in six states: California, Florida, Illinois, New Jersey, New York, and Texas. By 2005, it dropped by 20 percent.