New Report Reveals Illegal Immigrant Population Hit New High During Biden-Era Crisis

The number of illegal immigrants in the U.S. is estimated to have surged to more than 18 million after the Biden-era border crisis, according to a new research report by a hawkish immigration group, which also found an 11% increase in less than two years.

The report was produced by the Federation for American Immigration Reform (FAIR), which argues for lower levels of immigration overall. It estimates that, as of March 2025, there are approximately 18.6 million illegal immigrants living in the U.S.

That is 11% higher than an estimate the group published in June 2023, when it found that there were 16.8 million illegal immigrants. Overall, it estimates that the population has grown by 4.1 million or 28.2% since December 2020.

“As of 2025, American population growth comes almost entirely from unsustainably high levels of immigration, both legal and illegal,” the report says.

FAIR estimates that there were around 11.7 million illegal immigrants in 2013.

The group includes, as an illegal immigrant, anyone who does not have legal status like a visa or permanent residency, and notably also includes those who may be in the country illegally but given a lawful presence, like Temporary Protected Status or humanitarian parole.

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The report estimates the total number of illegal immigrants by using Census Data and compensating for what it argues is a history of undercounting those who arrive illegally, calculating an undercount of around 40%.

The report also concedes that “estimating the size, distribution, and characteristics of the illegal alien population is an inexact science.”

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