Fact Check: Did 20M undocumented immigrants enter US under Biden?
WASHINGTON, DC: Some prominent MAGA-aligned Republicans say as many as 20 million people crossed into the United States illegally during the Joe Biden administration.
The claim spread after Trump and White House officials said they plan to review all migrant cases approved under the previous administration. Read on to find where the claim started and whether it stands up to the facts.
Where did the claim originate?
Senior adviser to Donald Trump, Stephen Miller, told Fox News on Wednesday, November 26, that two National Guard members had been shot in Washington, DC, leaving one dead and the other in critical condition.
Miller then allegedly claimed that “the breaking news tonight” was that the government planned to speed up efforts to review “every single person added to this country over the last four years, all 20 million.”
His statement repeated a claim circulating in political commentary that 20 million people entered the United States illegally during the Biden administration and that officials are now reviewing all of those cases.
Alex Nowrasteh, Senior VP for Policy at the Cato Institute, allegedly wrote in a post, "Vice President JD Vance and a collection of online conservative commentators have argued that, as president, Joe Biden let in 20 or 30 million illegal immigrants, swelling their population to 30—50 million. These numbers are an exaggeration, but there was a large increase in the illegal immigrant population during the Biden administration."
The number has spread quickly across media and online discussions, raising questions about where it came from and whether it is accurate.
What do the facts say about the undocumented immigrant population?
Estimates from the nonpartisan Pew Research Center show that the undocumented immigrant population in the United States reached 14 million in 2023, the highest level on record.
Pew released this estimate in August, noting an increase from earlier counts that placed the undocumented population at about 11 million. The population had actually begun to decline during Trump’s presidency, when his administration enforced stricter immigration policies.
US Customs and Border Protection records “encounters” each time officers stop, arrest, or detect someone trying to cross the border without authorization. An encounter does not mean a person successfully entered the United States. It only confirms that authorities made contact with the individual.
Encounters can end in several ways: some migrants are expelled or returned to Mexico, others face formal deportation, and some are placed into processing that may or may not result in remaining in the country. Repeat attempts can also lead to multiple encounters for the same person, which raises the total without increasing the number of people who actually stay.
Because encounters track events, not new permanent residents, the numbers are often misinterpreted. Treating encounter totals as if they represent migrants who successfully entered and settled in the US creates a distorted picture of the undocumented population.
This misunderstanding has fueled political claims that rely on encounter totals as though they reflect long-term population growth, even though many of those counted are removed or never remain in the country.
Claim about undocumented immigrants is misleading
According to a Department of Homeland Security press release on October 27, 2025, more than 2 million undocumented migrants left the United States, including about 1.6 million who voluntarily self-deported and more than 527,000 who were formally removed.
Pew also reported that 53.3 million immigrants, both legal and undocumented, lived in the US in January 2025, making up 15.8% of the population. By June, departures and deportations outpaced new arrivals, reducing the immigrant population to 51.9 million, or 15.4% of all residents.
The claim that 20 million undocumented immigrants entered the United States during the Biden administration is misleading. While border encounters have been high, encounters do not equal successful entries, and the unauthorized population did not rise by 20 million. No public data or independent research supports that figure.
