Fact Check: Did 20 Million Illegal Immigrants Enter US Un...

By Billal Rahman

Immigration Reporter

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Several prominent Republicans in the MAGA world have claimed that as many as 20 million people entered the United States illegally during the Biden administration.

President Donald Trump and White House officials have said the administration is now planning to review all of these cases of migrants who entered the country under the previous administration.

The Claim

Stephen Miller, a senior adviser to Donald Trump, said on Fox News Wednesday after two members of the National Guard were shot dead in Washington, D.C, "The breaking news tonight is saying that his government is going to accelerate efforts to review every single person added to this country over the last four years, all 20 million."

This claim suggests that 20 million people entered the U.S. illegally during the Biden administration and that the government is now reviewing all of these cases.

This figure has circulated widely in political commentary and media reports, prompting questions about the accuracy of the number.

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The Facts

The undocumented immigrant population in the United States reached 14 million in 2023, the highest level on record, according to estimates from the nonpartisan think tank Pew Research Center.

The new estimate from Pew, published in August, represents a rise from earlier figures that placed the undocumented population at around 11 million. The study also found that the number had begun to decline during Donald Trump’s presidency as his administration implemented stricter immigration policies.

"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," Alex Nowrasteh, Senior VP for Policy at the Cato Institute, a libertarian think tank, wrote in a post.

U.S. Customs and Border Protection uses the term "encounters" to record every instance in which an individual is stopped, apprehended or otherwise detected attempting to cross the border without authorization. An encounter does not represent a successful entry into the United States; it only reflects that authorities made contact with a person at or between ports of entry.

Encounters can lead to a range of outcomes. Some individuals are quickly expelled or returned to Mexico, others are formally deported, and some individuals are placed into processing that may or may not result in a long-term stay. The totals can also include repeat crossers who are counted multiple times, further inflating the overall number.

Because encounters measure events rather than people who remain in the country, the figures are often misunderstood. Conflating encounter totals with the number of migrants who actually enter and settle in the United States can create a distorted picture of the undocumented population. This conflation has played a central role in political claims that treat raw encounter numbers as if they reflect permanent additions to the immigrant population, even though many of those recorded are removed or never remain in the country.

The Department of Homeland Security said more than 2 million undocumented migrants have left the United States, including about 1.6 million who voluntarily self-deported and more than 527,000 who were formally removed, according to a press release issued on October 27, 2025.

In January 2025, 53.3 million immigrants lived in the country, accounting for 15.8 percent of the population, according to Pew. But by June, departures and deportations outpaced new arrivals, reducing the immigrant population to 51.9 million, or 15.4 percent of all U.S. residents.

The Ruling

The claim that 20 million illegal immigrants entered the United States under Joe Biden is misleading. While border encounters have been high, encounters do not equal successful entry, and the total unauthorized population did not increase by 20 million during this period. The figure cited in the claim is not supported by publicly available data or independent analysis.