The establishment political consensus has long held that it’s impossible to rein in illegal immigration until Congress passes “comprehensive immigration reform.” The Congressional Budget Office has recently made clear that all it really takes is a president willing to enforce federal immigration laws, as he is constitutionally required to do.
The CBO recently revised its estimates concerning the number of illegal aliens entering or leaving the United States. More than a year ago, just before Inauguration Day, the CBO estimated that a net 1.1 million “other foreign nationals”—those lacking “a legal immigration status”—would be added to the U.S. population in 2025. Now the CBO has revised that estimate downward by a whopping 1.5 million illegal aliens—from an increase of 1.1 million to a decrease of 360,000. This downward revision of 1.5 million people is equivalent to the population of San Antonio.
Finally, a reason to check your email.
Sign up for our free newsletter today.
What caused this “significant reduction?” The congressional scorekeeper’s answer is clear. The decline was “driven largely by administrative actions taken since January 20, 2025.” The CBO particularly emphasizes an action that President Donald Trump took on his first day in office: “Executive Order 14165 reinstated the policy of Migrant Protection Protocols, which require people who want to apply for asylum in the United States to return to the territory from which they came.” The CBO adds, “That order also ended all categorical parole programs and ceased the use of the CBP One app as a method of paroling or facilitating the entry of people into the United States.”
Under President Joe Biden, illegal aliens who “arrived between official ports of entry”—that is, along the open (southwestern) border—“were generally released into the United States,” writes the CBO. It adds, “People could also use the CBP One app to schedule an appointment at a port of entry” and then “be released into the United States.”
The Trump administration almost immediately stopped the Biden administration’s lawless practice of releasing illegal aliens into the U.S. interior. This accounts for the CBO estimate that 1.5 million fewer illegal aliens were living in the U.S. at the end of 2025 than would have been the case with a continuation of Biden’s policies. The 46th president’s “equity”-based policies brought about a border crisis by design.
While the mainstream press emphasizes ICE raids and deportations, the Trump administration’s removal of aliens from the U.S. interior accounted for less than one-tenth of the CBO’s downward revision in net illegal immigration—it estimates that 120,000 people were removed from the U.S. interior in 2025. Far from being driven by deportations, more than 90 percent of the Trump administration’s success in reducing illegal immigration has come from limiting border crossings, per the CBO’s figures.
The CBO estimates that 540,000 illegal aliens arrived along the open border in 2024, between the ports of entry, and were released into the U.S. by the Biden administration. In 2025, such releases dipped to 20,000—a 96 percent decrease. Similarly, 960,000 illegal aliens arrived at the ports of entry and were released into the U.S. in 2024, compared with only 60,000 in 2025—a 94 percent drop. (Many of those released under Trump were unaccompanied minors, required by law to be released to sponsor families.)
What’s more, only about half of the 2025 releases occurred from February through December. Most of the releases at the ports, and many of the releases along the open border, occurred in January, when Biden was still in office for most of the month. In fact, roughly the same number of illegal aliens were released into the country during three weeks of Biden as during 49 weeks of Trump.
In addition, the Trump administration dramatically cut the number of people who evaded capture and snuck across the border. The CBO estimates that about 300,000 people escaped across the border in this manner in 2024 but only about 50,000 did so in 2025—an 83 percent reduction. In a 2023 immigration case, U.S. District Court Judge T. Kent Wetherell said the Biden administration’s “actions were akin to posting a flashing ‘Come In, We’re Open’ sign on the southern border.” When the Trump administration effectively unplugged that sign, the number of people trying to sneak across the border dropped dramatically.
In all, the CBO estimates that about 80,000 people lacking “a legal immigration status” were released into the U.S. last year (roughly half of them during the 20 days of Biden), while 50,000 snuck across the border and 260,000 overstayed their visas. Meanwhile, 400,000 decided to leave voluntarily, 120,000 were removed from the interior of the U.S., and 225,000 attained permanent legal status. That amounts to a one-year reduction in the illegal alien population of about 360,000, whereas the CBO had previously projected an increase of about 1.1 million.
The CBO now projects that over the first three years of the Trump administration, the number of illegal aliens living in the U.S. will decrease by 1 million (with reductions of 360,000 in 2025, 330,000 in 2026, and 330,000 in 2027). Over the last three years of the Biden administration, the CBO estimates a 5.7 million increase (2 million in 2022, 2.4 million in 2023, and 1.3 million in 2024) in the number of illegal aliens living in the U.S. That 6.7 million swing—from 5.7 million to negative 1 million—exceeds the combined populations of Los Angeles and Phoenix. That’s the difference between three years of Biden’s policies versus three years of Trump’s, according to the CBO.
The success that the Trump administration has had in reversing the flow of illegal immigration—simply by enforcing existing laws—was broadly thought to be impossible. Less than a year before Trump took office, the Wall Street Journal editorial board wrote that “the President needs Congress to fix the underlying incentives at the border.” A few months later, the Biden White House issued a fact sheet that began, “Since his first day in office, President Biden has called on Congress to secure our border.” When asked about illegal immigration during a 60 Minutes interview in October 2024, Vice President Kamala Harris said that “we need Congress to be able to act to actually fix the problem.”
It turns out that fixing the problem required only executing the laws already on the books—specifically the law requiring that asylum-seekers be detained while their cases are heard, rather than being released into the interior of the country. The Immigration and Nationality Act declares that “if an alien asserts a credible fear of persecution, he or she shall be detained for further consideration of the application for asylum.” Supreme Court Justice Samuel Alito writes that these detention “requirements, as we have held, are mandatory.”
The foreign-born portion of the U.S. population rose from 4.7 percent in 1970 to 16.2 percent in 2023, and probably reached about 16.8 percent in 2024—easily breaking the previous all-time record of 14.8 percent set in 1890, at the height of the great waves of nineteenth-century immigration. It will take many years of enforcing existing immigration laws to see that percentage dip back down to something approaching historical norms. But as the CBO now acknowledges, the Trump administration is making significant headway—even if the congressional scorekeeper didn’t see it coming.