A new study finds that America's illegal immigrant population has actually decreased during the past decade as the result of more than 1 million people voluntarily self-deporting back to Mexico.



"The total undocumented population in the United States continued to decline in 2018, primarily because large numbers of undocumented residents returned to Mexico," the executive summary of a study announced by the Center for Migration Studies of New York on Wednesday states. "From 2010 to 2018, a total of 2.6 million Mexican nationals left the US undocumented population; about 1.1 million, or 45 percent of them, returned to Mexico voluntarily."



The study also found that, during the eight-year window, "The undocumented population from Mexico fell from 6.6 million in 2010 to 5.1 million in 2018, a decline of 1.5 million, or 23 percent."

As a result of the decreased overall illegal immigration population, the study claims, the state of California saw its own illegal population decline by 600,000 from 2010 to 2018, and New York state saw a decrease of 230,000. However, Texas actually saw an increase of 77,000 in its illegal immigrant population over the same time frame, the report adds.

"There's a widespread assumption that everyone wants to come to the United States and no one ever leaves, but that's never been true," Robert Warren, who conducted the study, said in a story at the Washington Times. "There has always been a return flow, but until recently we weren't able to measure it well in the undocumented population."

In order to estimate the United States' illegal immigrant population during the described years, the study employed a series of five steps to derive estimates based on census and survey numbers.

Given the clandestine nature of illegal immigration, it's impossible to know exactly how many illegal immigrants are in the United States at any given time and estimates have varied. As a recent Department of Homeland Security Office of Inspector General report pointed out, DHS estimated a total 12 million in 2015 but a 2018 academic study placed the estimation at 22.1 million.

Furthermore, it's also important to keep in mind that the CMS study analyzes only up until 2018, and therefore doesn't account for immigration flows that happened afterward. For example, 2019 saw overwhelmingly high numbers of apprehensions at the southwest border which peaked in May and eventually leveled off to Obama-era levels towards the end of the calendar year.