As Homeland Security Secretary Kristi Noem has been making the rounds on Capitol Hill this month, she’s tossed out some startling statistics — and none more striking than her estimate that there are 20 million illegal immigrants now in the U.S.
“We don’t know for certain, but we believe it could be upwards of 20 million people that could be in this country illegally,” Ms. Noem told senators in one hearing.
At a Cabinet meeting, meanwhile, she told the president there were “20 to 21 million people that need to go home.”
That’s larger than what most analysts say, but at least some of those experts also say that with the Biden border surge, it’s not as outlandish an idea as it would have seemed just a few years ago.
“Biden blew the top off everything,” Stephen A. Camarota, research director at the Center for Immigration Studies, told The Washington Times. “The idea of 20 million now is not crazy anymore.”
His current figure is nearly 16 million, but he said the uncertainties of the Biden years have made the actual figure tough to get at.
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For much of this century, through the late Bush and Obama years into the first Trump term and even the start of Mr. Biden’s tenure, official estimates put the number at between 10 million and 12 million. A few outliers with what might best be described as novel statistical approaches put the figure much higher.
Mr. Biden’s tenure clearly changed that, though how much is the subject of heated debate, particularly online.
When Mike Davis, a Trump loyalist and head of the Article III Project, recently posted a critique of the Supreme Court’s immigration rulings and included an estimate of 10 million illegal immigrants, the comments erupted into a bidding war.
“Ten million? I believe there are at least 20 million,” said one.
“40M+” said another.
“No. There are at least 50 million. We would be lucky if there were only 10 million,” countered a third.
“I bet my retirement more near 100,000,000,” said still another.
Elsewhere, White House Deputy Chief of Staff Stephen Miller has estimated that the Biden administration let in 15 million illegal immigrants. Vice President J.D. Vance says “approximately 20 million” were “allowed” into the country.
Those are higher than what the official figures would suggest.
Adding all the unauthorized migrants encountered by Customs and Border Protection from January 2021 to December 2024 comes to 10.9 million. Some other percentage are what’s known as “gotaways,” who evaded capture. Some were detected — those are the known gotaways — and others weren’t.
That means the total of illegal entries is likely millions higher.
But a number of the CBP encounters are duplicates — illegal immigrants who tried, were caught and then tried again —being counted for each attempt.
Many migrants came on legal visas but overstayed and have become illegal immigrants.
All of that makes trying to calculate the total population using arrivals and departures too fraught with sources of error.
Which is why folks like Mr. Camarota and Robert Warren, a demographer at the Center for Migration Studies of New York, turn to Census Bureau data for snapshots in time.
Mr. Warren uses the Census’s American Community Survey for his estimates, and he said the higher estimates being tossed around by Ms. Noem and others are unfathomable.
“The secretary probably should read her report from her agency,” said Mr. Warren, who assists Homeland Security with its official estimates and co-wrote that latest report, released in April 2024.
It looked at the years from 2018 to 2022 and found the unauthorized population stood at 11.6 million in 2018, dipped to 10.5 million in 2020, and started rebounding to 11 million by 2022.
Mr. Warren said the estimates of more than 20 million people simply cannot be correct, given what he sees in the census data.
That shows there are only about 20 million noncitizens who live here and who arrived after 1981. Given the 1986 amnesty and some other factors, that 20 million, give or take some adjustments for a census undercount, represents the absolute upper limit on illegal immigrants.
But since a significant percentage of that 20 million are also here with some legal status, the number is going to be lower.
“So if you’ve got 20 million that comprises the entire possible undocumented population, and you know 10 million of them are legal, you’ve got very little leeway unless you think the Census Bureau misses half of the undocumented population,” he said.
Mr. Camarota agreed that the figure had been steady for most of this century, but he said the Biden era “shows an explosion” of noncitizen Hispanics.
He said the 20 million number is still probably too high. If that were real, he said it would show up in secondary indications such as school enrollment or births, given that the surge of border jumpers was so heavily Latin American and immigrants from that region tend to have higher birth rates.
But then again, he said, maybe the new arrivals are more heavily men, or the fertility rates for those populations have changed.
“I would be willing to bet a lot of money it’s between 14 and 17 [million] and around 16 is about right,” he said.
Another wrinkle is who is counted as being in the U.S. illegally. That turns out to be a tricky question.
Some analysts would say someone here under the Obama-era Deferred Action for Childhood Arrivals wouldn’t count as an illegal immigrant because DACA granted them a stay of deportation. The same holds true for those here under Temporary Protected Status, those who have applied for asylum or the millions granted “parole” by the Biden administration.
“What’s your way of estimating the illegal population?” Mr. Camarota said. “We have such a convoluted immigration system that we have enormous numbers of people who are technically inadmissible aliens, don’t have a legal right to be here, but are allowed to stay and work.”
The Federation for American Immigration Reform has the most aggressive estimate on the books right now, chiefly because it estimates a massive undercount — that’s the number of illegal immigrants who don’t show up in the census.
FAIR, which uses a combination of American Community Survey data and the Current Population Survey, another Census Bureau product, put the illegal immigrant population at 18.6 million as of March.
The Migration Policy Institute and the Pew Research Center, two other major players in the field, use the American Community Survey, which means their latest estimates only go to 2022. MPI put the figure at 11.3 million, while Pew pegged it at 11 million.
