Fact check: Have 5 million migrants crossed the southern border since Biden took office?

Political candidates continue to claim 5 million people have crossed the border since Joe Biden became president, with the suggestion that they are now living in the U.S.

Where did the 5 million number come from, and how accurate is it?

One of the main sources for the number is the Heritage Foundation, an influential conservative think tank.

The Arizona Republic spoke with Mark Morgan, who explained how he came up with the estimate. He worked for former President Donald Trump as the acting commission of U.S. Customs and Border Protection, the agency that includes the Border Patrol, which he also commanded under former President Barack Obama.

Morgan is now a fellow at the Heritage Foundation and the Federation for American Immigration Reform, which pushes for reducing all immigration.

The Republic also reached out to the nonpartisan Migration Policy Institute and the Cato Institute, a libertarian think tank. Both organizations said the 5 million number is inaccurate.

Estimating the actual number of people who have crossed the border is not an exact science. Coming up with an estimate depends on how Customs and Border Protection data is interpreted.

While there is no question the Border Patrol has logged a record number of encounters, each encounter does not represent a unique individual because some migrants are caught multiple times. Border Patrol encounters also include the huge surge in families and unaccompanied minors who turn themselves into agents, rather than attempting to evade detection. 

The agency also does not publish some critical data, notably the number of migrants who cross but are not caught, making it even murkier to estimate the total number of people who cross. 

The case for 5 million border crossings

Here is how Morgan came up with the 5 million number, which he believes is a "conservative underestimate."

The Border Patrol has logged 3.8 million encounters with migrants since Biden took office in January 2021, including nearly 2.4 million in fiscal year 2022 through September and just over 1.4 million in fiscal year 2021, according to CBP data. The 3.8 million number does not include Border Patrol encounters during the first four months of fiscal year 2021, which fell under Trump.

Morgan rounded up the 3.8 million to 4 million to 4.2 million including October's BP encounters. October CBP data hadn't been published yet, but encounters are averaging about 200,000 a month.

He then added another 1 million "known got-aways" to come up with an estimate of 5.2 million illegal border crossings since Biden took office. 

Known got-aways are migrants who were spotted by agents by sight, through surveillance cameras or other technology, but were not caught, Morgan said. The agency does not publish data on got-aways. Morgan's got-away estimates are based on information he has received from the Border Patrol and got-away data reported by media outlets, he said.

"So that is where the 5 million has come from," Morgan said.

But Morgan believes the number of illegal border crossings over the past 20 months could be as high as 6.2 million when "unknown got-aways" are factored in. Unknown got-aways are migrants who crossed the border but were not detected by the Border Patrol.

Morgan estimates that there could have been an additional 1 million "unknown got-aways" since Biden took office.

On top of that, Morgan estimates that another 200,000 "turn-backs" took place during the past 20 months. Turn-backs are migrants who entered the U.S. but then returned across the border on their own. 

"So best case scenario it's 5.2 million in the last 20 months, worst case scenario, it could be 6.2 million," Morgan said. "That's why I say the 5 million number is I think a very conservative number."

The argument against 5 million border crossings

Others, however, say the 5 million number is overblown and deceptive, because it includes migrants who crossed the border illegally but were quickly expelled from the U.S. under a public health rule called Title 42 implemented during the pandemic.

There have been almost 1.9 million expulsions under the Biden administration through the end of October of this year, Michelle Mittelstadt, a Migration Policy Institute spokesperson, said. 

The 5 million number also does not reflect the actual number of individual people who crossed the border illegally. Border Patrol encounters reflect the number of times agents encountered a migrant, including the same migrant encountered multiple times after being expelled and returning.

"CBP encounters reflect events, not individuals. With recidivism rates in FY 2022 standing at 26%, that means that more than one out of every four encounters is of someone who was previously expelled or otherwise removed by DHS," Mittelstadt said in an email.

David Bier, associate director of immigration studies at the Cato Institute, also noted that about half of Border Patrol encounters involve migrants who turned themselves into agents to request asylum after crossing illegally. 

Of the 3.8 million Border Patrol encounters since Biden took office, about 1.9 involved migrants placed in removal proceedings under Title 8 of the immigration code, including asylum seekers.

Unlike migrants who try to evade the Border Patrol, asylum seekers who turn themselves in undergo fingerprinting and other biometric processing so there is a record of them, Bier said.

"So they are not seeking to evade detection. They're looking to turn themselves in and request to be processed by the Border Patrol. And that includes biometrics and background checks and everything else that every security agency does when they come in contact with a non-citizen," Bier said.  

What's more, not all of the 1.9 million migrants processed under Title 8 have been allowed into the U.S. to pursue asylum claims or otherwise appear in immigration court, Mittelstadt said. Some have faced expedited removal, some have been deported, and some have been placed into immigration detention, she said.

Repeat crossers affect the data, Border Patrol resources

Morgan, however, said it doesn't matter whether Border Patrol encounters reflect total encounters or unique individuals because the same amount of resources have to be spent each time an encounter is made.

"The same resources are pulled away, the same processing happens," Morgan said. "So if that individual comes back again 20 days later, the agent is still pulled off the line, off the national security mission, leaving the border more open." 

What's more, the border is left less guarded while Border Patrol agents are pulled off the line to process the surge in asylum seekers who have arrived under the Biden administration, Morgan said.

Bier agreed that each time a Border Patrol agent makes an encounter, the same resources are expended, whether that person is a first time crosser or repeat crosser.

"If Border Patrol is arresting somebody, it's certainly taking up Border Patrol resources to do that. That's indisputable," Bier said. "And Border Patrol is making more arrests than they've ever made."

Bier blamed the surge in Border Patrol arrests, however, on poor policy on immigration, including the failure of Congress to enact reforms that allow workers and asylum seekers to enter legally rather than illegally, which would free up agents to focus on public safety and national security threats. 

The Border Patrol "should only have to worry about trying to arrest serious criminals and not have to worry about people who are trying to seek safety and opportunity here," he said. 

How many migrants in the U.S.?

There is also dispute over the number of migrants who entered illegally under the Biden administration and are now living in the U.S.  

Morgan estimates that number at 3 million to 4 million, including families and unaccompanied minors who were released after they crossed illegally, turned themselves into Border Patrol agents and requested asylum in the U.S. plus known and unknown got-aways.

Mittelstadt estimated that about 1 million asylum seekers have been admitted to the U.S. under the Biden administration, similar to an estimate by the New York Times. She did not estimate the number of got-aways living in the U.S.

Bier, of the Cato Institute, disputed Morgan's 3 million to 4 million estimate.

He estimates the number of asylum seekers and got-aways now living in the U.S. since Biden took office at 1.8 million to 1.9 million.

He believes that Morgan's estimate of 1 million unknown got-aways is inflated because it has become harder to cross the border illegally over the past 20 years because of the increase in agents and technology. He believes the number of unknown got-aways to be less than half of his estimate of 750,000 known got-aways.

"We have drones flying in the skies. We have 24/7 surveillance towers on the border. We have well over double the number of agents. So the amount of eyes and surveillance is so much greater today than it was back then that the rate of of non-detection has gone down," Bier said

He noted that census data shows that the total immigrant population has increased by about 2.85 million under the Biden administration. The total includes immigrants who are naturalized U.S. citizens, legal immigrants and undocumented immigrants.

"It's not true that 5 million people have crossed the border and are now living in the United States" since Biden took office, Bier said. "The number is a few million less than that."

Reach the reporter at daniel.gonzalez@arizonarepublic.com or at 602-444-8312. Follow him on Twitter @azdangonzalez.