Who said this? “If you don’t have any borders, you don’t have a nation.” The speaker went on, “Trump did a better job. I don’t like Trump, but we should have a secure border. It ain’t that hard to do. Biden didn’t do it.”

It was Sen. Bernie Sanders (I-Vt.) in characteristic candor. If, as Milton Friedman argued, you can’t have open borders and a generous welfare state, Sanders, as a self-described socialist, prefers the welfare state.

The facts at this point are not in much doubt. The Pew Research Institute, not an anti-immigration outfit, estimated that there were 10.2 million “unauthorized” immigrants (members of groups not approved for legal immigration) in the United States in 2019, the year before former President Joe Biden was elected, and 10.5 million in 2021, the year he took office.

That number, as Pew’s Jeffrey Passel and Jens Manuel Krogstad wrote, grew to 14 million in 2023, “the largest two-year increase in more than 30 years of our estimates.”

The illegal population probably peaked at about 14.5 million in early 2024, when the Biden Democrats, who said they had no alternative to their open-border policies without new legislation, suddenly decided they actually could clamp down using existing legislation.

Let’s put that in a longer perspective. Pew estimated that the illegal immigration population increased from 3.5 million in 1990 to a peak of 12.2 million in 2007-08, the years housing prices and financial markets crashed. Suddenly, net migration from Mexico turned negative, and the illegal population fell through attrition until Biden took office. Then it rose from 10.5 to 14.5 million.

That number has trended downward since President Donald Trump took office last January. Earlier this month, in a report for the Center for Immigration Studies, which opposes illegal immigration and favors lower legal immigration, analysts Steven Camarota and Karen Zeigler estimated, based on multiple government statistics, that the foreign-born population declined by 2.2 million since Trump was inaugurated in January. Presumably, almost all of this change can be attributed to illegal immigrants.

This provides some backing for the Trump Department of Homeland Security’s claim that it removed 527,000 illegal immigrants and that 1.6 million “have voluntarily self-deported.”

That’s obviously an estimate, but it’s not improbable. If 4 million additional illegal immigrants were incentivized to arrive in the first three-plus years of the Biden administration, as compared to a net decline in the 12 years from 2008 to 2020, it’s plausible that 2 million were compelled or decided to leave due to the highly publicized and aggressive actions in 2025.

That’s not an uncontroversial process, of course. Government is a blunt instrument, and no doubt Immigration and Customs Enforcement agents have wrongfully detained some genuine citizens and legal immigrants. Some people who have lived quietly and constructively, though illegally, for many years have had their lives overturned. There’s an argument that Trump officials have acted too aggressively and in disregard of the limited rights that illegal immigrants have.