The foreign-born population in the United States has fallen by 2.9 million since January 2025, a decline the Center for Immigration Studies calls unprecedented and attributes primarily to a sharp drop in the number of illegal immigrants.
The figures come from the Census Bureau's Current Population Survey, a monthly household survey that tracks demographic shifts across the country. CIS, a Washington-based research organization that advocates lower immigration levels, reviewed the data and published its analysis estimating that the illegal immigrant population specifically fell by 2.3 million over the same period, from 15.8 million in January 2025 to 13.5 million by July 2026.
That eighteen-month window covers President Trump's return to office and his enforcement push against illegal immigration. And the scale of the reversal becomes clearer against the backdrop of the prior administration: an estimated 8.3 million foreign-born individuals entered the country during Joe Biden's presidency.
CIS described the current immigration rate as sitting at "relative zero percent", a level the organization said has not been recorded since the 1930s. The foreign-born population tracked by the CPS includes naturalized citizens, lawful permanent residents, long-term temporary visitors, and illegal immigrants. All categories are captured in the same survey, and the net 2.9 million decline reflects the combined movement across every one of them.
The net change, CIS noted, accounts for new arrivals offset by deportations, voluntary emigration, legalizations, and natural mortality. In other words, people are still coming in. But the outflow, driven in large part by illegal immigrants leaving, has overwhelmed new entries by a wide margin.
CIS offered this summary of its findings:
"Since January 2025 when President Trump took office the government's monthly household survey, officially called the Current Population Survey (CPS), shows an unprecedented 2.9 million decline in the foreign-born population, naturalized citizens, lawful permanent residents, long-term temporary visitors, and illegal immigrants. We preliminarily estimate that the illegal immigrant population has fallen 2.3 million."
The organization added that the bulk of those leaving were migrants from Latin America who had arrived in the United States after 1980. Roughly 44 percent of the departures were working-age adults. The rest were non-working family members and children.
The Trump administration has pursued enforcement on multiple fronts. The State Department alone has revoked more than 175,000 visas under a continuous vetting program, one piece of a broader apparatus that appears to be reshaping who stays and who goes.
Not everyone accepts CIS's reading of the numbers at face value. Unnamed activists who oppose stricter immigration enforcement have disputed the analysis, arguing that CIS is extrapolating too much from the CPS because the survey does not directly measure the actual size of the foreign-born population. The CPS is a household survey, not a census count, and participation is voluntary, which means people who fear contact with the government may simply stop answering the door.
CIS addressed that objection head-on:
"We have no evidence that immigrants are not responding to the CPS. But even if half of the decline in the overall foreign-born population or in the illegal immigrant population is due to an increased unwillingness on their part to participate in the survey, it would still be the case that the actual fall-off in their numbers is very large and could reasonably be described as unprecedented."
That concession matters. Even by the most skeptical reading, cutting the headline number in half, the decline would still represent roughly 1.45 million fewer foreign-born residents in eighteen months. No recent administration has produced anything close to that trajectory.
Congressional Republicans have moved to back the enforcement push with funding. A $70 billion immigration enforcement bill cleared the Senate after weeks of Democratic resistance, giving the administration additional resources to sustain the pace of removals and border security operations.
The sheer volume of foreign-born arrivals during the Biden years is the context that makes the current reversal so striking. CIS noted that an estimated 8.3 million foreign-born individuals entered the country under Biden, a surge that strained housing markets, school systems, municipal budgets, and public patience in communities across the country.
A Federal Reserve study found that the Biden-era surge in illegal immigration contributed to higher home prices and rents for American families, quantifying what many voters already felt in their monthly bills.
CIS put the bottom line plainly:
"The bottom line is that the household survey shows a huge decline in the foreign-born, which seems to be due primarily to a dramatic decrease in the number of illegal immigrants in the country."
The organization's preliminary estimate pegs the current illegal immigrant population at 13.5 million, still a large number, but sharply lower than the 15.8 million it estimated at the start of the Trump administration. The decline suggests that enforcement, combined with the credible expectation of enforcement, has changed the calculus for millions of people who entered the country unlawfully.
The administration has also moved on related fronts, including executive orders targeting birth tourism and narrowing birthright citizenship, signaling that the broader policy architecture extends well beyond deportation flights.
Several questions remain. The CPS data does not break out how much of the net decline comes from deportations versus voluntary departures. CIS acknowledged that its 2.3 million illegal immigrant estimate is preliminary, and the organization did not publish a margin of error or confidence interval. The identities of the activists disputing the findings, and the full substance of their methodological critique, are not specified in the report.
Still, even with those caveats, the direction is unmistakable. A separate concern, the integrity of voter rolls in states with large illegal immigrant populations, has drawn its own scrutiny, with a DHS memo revealing that more than 250,000 illegal immigrants were registered to vote in four states that refused access to a federal verification database.
The CPS is not a perfect instrument. No single survey captures every person in a country of 330 million. But the trend line it reveals, a nearly three-million-person drop in the foreign-born population in a year and a half, is too large to dismiss as statistical noise, even by the critics' own logic.
When the law is enforced and the border is treated like a border, people respond. That used to be common sense. Now it is data.
