The number of unauthorized immigrants in the U.S. fell to its lowest level in more than a decade, according to a study published Tuesday by the Pew Research Center based on 2016 government data, falling from 12.2 million at its peak in 2007 to 12.2 million in 2016, and is no the lowest total since 2004.
An analysis of the undocumented immigrant flow found that there was an average of 386,000 annual arrivals for the 2011-16 period, compared with 715,000 for the 2002-07 period, amounting to a 46% decline.
The decline is due almost entirely to a sharp decrease in the number of Mexicans entering the country illegally, it found. While the Mexican border remains the main entry point for migrants, more migrants now come from El Salvador, Guatemala and Honduras.
Pew Research Center’s estimate includes more than a million people who have temporary permission to stay and work in the U.S. under the DACA and TPS programs that the Trump adminsitration has sought to terminate.
The number of Mexicans declined by 1.5 million people from 2007 to 2016, although Mexico still accounts for 5.4 million undocumented immigrants, or roughly half of the U.S. total.
"Increasingly, unauthorized immigrants are likely to be long-term U.S. residents: Two-thirds of adult unauthorized immigrants have lived in the country for more than 10 years," the study found. "By 2016, an unauthorized immigrant adult had typically lived in the U.S. for 14.8 years, compared with a median 8.6 years in 2007," it added.
The Pew Research Center based its estimates on official U.S. data sources, including census counts, birth records, school enrollment figures and tax data, as well as Mexican censuses and surveys.
The study said that "a rising share" of undocumented immigrants arrive legally, but overstay visas, though it was it was unclear how many they are. "Among unauthorized immigrants in the Center’s estimates who arrived in the previous five years, the share who are likely to be people who overstayed their visas probably grew substantially between 2007 and 2016 – to the point where they probably constituted most of the recent unauthorized immigrant arrivals in 2016," it said.
"Census data do not indicate whether unauthorized immigrants arrived with legal visas. But there is growing evidence about immigrants with expired visas from recent analyses by the U.S. Department of Homeland Security," it added. But the data does show that the vast majority of overstays - almost 90% – are from places other than Mexico and Central America.
"For Mexico, there were almost four times as many apprehensions as overstays, even with the very large drops in Mexican apprehensions. For the three Northern Triangle nations, there were about 10 times as many apprehensions as overstays in 2015-17 government data," the Pew Center said.