Illegal Immigrant Population Down 1 Million Since Trump Took Office, Research Group Says

A new survey-based estimate shows a steep falloff in a key group used as a proxy for the illegal immigrant population in the United States.

Customs and Border Protection agents guide illegal immigrants onto a C-17 Globemaster III for a removal flight at Fort Bliss, Texas, on Jan. 23, 2025. Army Sgt. 1st Class Nicholas J. De La Peña/Dept. of Defense

Roughly 1 million illegal immigrants have left the United States since January, the month President Donald Trump returned to office, according to a new study by the Center for Immigration Studies (CIS).

The findings come as the Trump administration intensifies its efforts to ramp up deportations, targeting large cities with so-called “sanctuary” policies and resuming operations at farms, hotels, and other businesses.

CIS, a nonprofit research group that analyzes U.S. immigration policies, said in a June 19 report that the estimated decline appears tied to the Trump administration’s early immigration enforcement push.

“The number of illegal immigrants has fallen by 1 million since the start of the year, perhaps due to their leaving in response to President Trump’s election and stepped-up enforcement efforts,” CIS wrote. “The decline was caused by a falloff in the number of noncitizens from Latin America who arrived in 1980 or later, a population that overlaps significantly with illegal immigrants.”

To arrive at its estimate, CIS analyzed monthly household survey data from the Bureau of Labor Statistics’ Current Population Survey (CPS), focusing on a subset of respondents—noncitizens from Latin America who entered the United States after 1980. This group, CIS noted, is commonly used by federal agencies and researchers as a proxy for estimating the illegal immigrant population. By subtracting estimates of legally present individuals from this total, the group calculated a net decline of 957,000 between January and May.

“Our preliminary estimate is that there are 14.8 million illegal immigrants in the country in May 2025, 1 million fewer than we estimated in January of this year,” the CIS report stated.

Still, CIS emphasized that its findings are preliminary and should be interpreted with caution. While the drop in noncitizens is statistically significant, the decline in the broader foreign-born population is not.

The group also acknowledged that heightened enforcement may have made some immigrants—especially those here illegally—less likely to participate in government surveys or to identify themselves accurately. Moreover, some of the administrative data needed to refine the May estimate has yet to be released.

And while CIS concluded that the data “strongly suggest” that Trump’s enforcement stance played a key role in the drop, it acknowledged it cannot definitively prove causation.

Meanwhile, estimates of the total illegal immigrant population vary widely—from about 11 million to more than 30 million—depending on the source and methodology. The Department of Homeland Security (DHS) estimated that 11 million illegal immigrants were in the country as of January 2022. President Trump has said that the true figure could be as high as 21 million, while Secretary of State Marco Rubio suggested that the number could be up to 30 million.

The CIS report comes just days after Trump directed his administration to mobilize “every resource” behind what he called “the single largest Mass Deportation Program in History,” prioritizing sanctuary cities such as Los Angeles, New York, and Chicago that have local policies inconsistent with federal immigration enforcement.

“Our Federal Government will continue to be focused on the Remigration of Aliens to the places from where they came,” Trump wrote in a post on Truth Social, adding that ICE, Border Patrol, the Pentagon, and other agencies had his “unwavering support” to “get the job done.”

Illegal border crossings have plummeted since Trump returned to office, but he has expressed frustration with what he views as the slow pace of removals. Amid the president’s latest deportation push, DHS confirmed it would continue conducting enforcement operations at farms, hotels, and other worksites—particularly those suspected of harboring criminal illegal immigrants.

Meanwhile, May marked a significant milestone: For the first time since recordkeeping began, Customs and Border Protection (CBP) reported zero illegal immigrants released into the United States. In a June 17 statement, the agency called the development a “staggering drop” from the more than 62,000 illegal immigrants released in May 2024.

CBP also said agents encountered just 8,725 illegal immigrants crossing the southwest border between ports of entry last month—a 93 percent decline from May 2024, when agents recorded 117,905 encounters.

“Encounter numbers continue to hold at historic lows, reflecting a border that is more secure, more controlled, and hitting unprecedented levels of operational success,” CBP said.