CIS Report: US Foreign-Born Population Fell 2.9 Million Since January 2025

The Numbers

The foreign-born population living in the United States fell by an estimated 2.9 million people between January 2025, when President Donald Trump took office, and July 2026, according to a Center for Immigration Studies (CIS) analysis of the Census Bureau's Current Population Survey released Thursday, September 3.

The foreign-born category includes naturalized citizens, green card holders, people on long-term visas, and illegal immigrants. CIS estimates illegal immigrants accounted for the bulk of the drop, falling from 15.8 million in January 2025 to 13.5 million in July 2026, a decline of roughly 2.3 million, or 14.6 percent.

"The best data we have shows an enormous decrease in the total foreign-born population, with most of the falloff among illegal immigrants," said Steven Camarota, CIS director of research and the report's lead author. "Regaining control of the border and robust interior enforcement has partly undone the huge increase in the illegal immigration that took place during the border surge."

That prior surge was substantial. CIS says the foreign-born population grew by 8.3 million between January 2021 and January 2025 under President Joe Biden, the largest four-year increase in the country's history, with the illegal immigrant population alone rising by an estimated 5.6 million over that same stretch.

Enforcement Numbers Behind the Shift

CIS points to two enforcement trends driving the reversal. Interior removals more than tripled compared with the final stretch of the Biden administration, up by roughly 207,000. Voluntary departures — migrants leaving on their own, often ahead of deportation proceedings — hit 89,494 in Trump's first 16 months, compared with 11,977 in Biden's final 16 months.

CIS says enforcement actions alone don't fully explain the size of the drop, meaning a significant share of the decline likely reflects migrants choosing to leave the country voluntarily rather than risk arrest.

Trump touted the border numbers directly in a Thursday interview with GB News, saying, "I closed our border. We haven't had a person come in illegally into our country through the southern border in 17 months... Nobody gets in."

Not a One-to-One Labor Market Hit

Only 44 percent of the people who left the foreign-born population count were workers, according to CIS. The foreign-born workforce shrank by just under 1.3 million, while the non-working population — children, retirees, caregivers — fell by about 1.6 million.

This means the labor market impact is smaller than the headline 2.9 million figure suggests, and CIS notes it may help explain why business surveys haven't shown an equally dramatic drop in employed workers.

The Caveats CIS Itself Flags

CIS is not a neutral government agency. It describes itself as an independent research organization founded in 1985 with a "pro-immigrant, low-immigration" mission, and it has testified before Congress more than 150 times pushing for lower immigration levels. Its data comes from a real federal survey, but its framing and advocacy priorities are its own.

CIS itself cautions that the July 2026 foreign-born estimate carries a margin of error exceeding 1 million people, meaning the true figure could be meaningfully higher or lower than 2.9 million. The group also acknowledges a competing explanation: immigrants, especially those in the country illegally, may simply be less willing to answer a government survey during an enforcement crackdown, which would shrink the measured population without anyone actually leaving.

CIS says it looked for evidence of that effect and didn't find it. Survey response and refusal rates didn't move in step with the population decline. The group concedes that even if half the drop were attributable to survey non-response, the remaining decline would still be historic.

Pro-immigration advocates, as Breitbart and the Tennessee Star both noted in their coverage, dispute CIS's reading altogether, arguing the Current Population Survey isn't designed to measure the actual size of the immigrant population and that CIS is extrapolating beyond what the data can support.

The entire measured decline was concentrated among Latin American non-citizens who arrived after 1980, a group CIS says overlaps heavily with the illegal immigrant population. If accurate, that would mark the first negative net migration period in the U.S. since the 1930s.

What isn't settled is how much of the 2.9 million reflects people who actually left the country versus people who simply stopped answering a Census Bureau phone call. The Census Bureau has not issued its own competing estimate of the foreign-born population for this period, and the next scheduled CPS releases will be the real test of whether the trend CIS identified holds up or narrows once fuller data comes in.