The number of undocumented migrants living in the United States has fallen to 10.7 million, the lowest since 2004, according to a Pew Research Center study, which attributed the decline to a big drop in undocumented Mexicans.
Pew, which based its latest findings on government figures from 2016, said the number of undocumented immigrants in the United States peaked in 2007 at an estimated 12.2 million people.
Between 2007 and 2016, the number of Mexicans in the United States illegally plummeted by 1.5 million, according to the study released Tuesday.
Nevertheless, people of Mexican origin still account for half of all undocumented migrants in the United States -- about 5.4 million people in 2016, Pew said.
Two-thirds of undocumented adults have been living in the United States for more than 10 years, a figure that has been rising sharply since 2007.
The number of undocumented migrants from Central America, however, rose by 375,000 between 2007 and 2016, according to Pew.
US President Donald Trump has made illegal immigration a signature issue since his 2016 presidential campaign, which he began with accusations that Mexico was sending drug traffickers, criminals and rapists across its northern border.
This year, he used the approach of a migrant caravan from Central America as a foil for his views ahead of the November 6 midterm election in the United States, evoking images of an "invasion."
On Wednesday, the US Department of Homeland Security asserted, without providing evidence, that there are "over 600 known criminals and gang members in the caravan." The Department added that agents had arrested a Honduran man suspected of being in the US illegally who admitted to being a member of the MS-13 gang, which Trump has regularly cited as a threat to the United States.