Why Trump’s math on immigration is all wrong, in 7 charts

Not undocumented.
Not undocumented.
Image: Reuters/Jose Luis Gonzalez
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For years Americans have looked at how many people border patrol agents catch as an indicator of undocumented immigration.

Since October, those numbers—known officially as “apprehensions”—have more than doubled compared to the same period the previous year to nearly 600,000 people. The surge prompted US president Donald Trump to threaten Mexico with import tariffs if authorities in that country don’t intercept more immigrants before they cross the Rio Grande.

“This sustained influx of illegal aliens has profound consequences on every aspect of our national life—overwhelming our schools, overcrowding our hospitals, draining our welfare system, and causing untold amounts of crime,” he said in a statement last week announcing the tariff strategy.

The strategy is questionable, both legally and in practice. And so is Trump’s math.

He is missing some pretty crucial figures, starting with the number of undocumented immigrants who actually settle and live in the United States. For years, that population has been shrinking. He also needs to subtract asylum seekers, who account for a large share of the intercepted immigrants. Under US and international law, they have a right to legally stay in the United States until a judge rules on their case, regardless of whether they entered the country illegally.

We took a historic dive into immigration data and found why Trump’s narrative doesn’t add up. Here are the holes, in seven charts:

The long view

The number of border crossers is rising, but remains historically low. The reason for this is the collapse in the number of Mexicans trying to sneak into the United States. Better opportunities and lower fertility rates in Mexico cut down the number of people desperate to leave. On the US side, the Great Recession dried up jobs, and increased border security made it harder to get in.

It would take many more Central American caravans for the the number of border apprehensions to reach the historic high of nearly 1.7 million from the 1980s.


Other than Mexican

These days, it is people from other countries who are shaping border traffic. They include Central Americans, who now account for well over half of apprehensions along the border. That’s partly because US immigration authorities are taking more Central Americans into custody, but mostly because they are arresting fewer Mexicans.

Most of these migrants are fleeing violence and poverty in the Northern Triangle, the trio of countries that include Guatemala, Honduras, and El Salvador.  

The number of apprehended immigrants from that region is up, but that doesn’t mean illegal immigration is rising.  Trump is leaving out a key distinction between apprehensions in the past and today. What they reflect is changing.

Back when Mexican economic migrants were the most common type of border crosser, apprehensions acted as a proxy for undocumented immigration—if not a very good one. At that time, it was much easier to evade the Border Patrol. So, observers looked at the number of people being caught for clues on how many people overall were making the trip north.

These days border patrol agents are far more effective at intercepting immigrants. In fact, they don’t even have to chase after them. Many Central Americans actually turn themselves in to request asylum.

The profile of “apprehended” immigrants has also changed. More than half of the Central Americans intercepted at the border since last October were families traveling with children, not men looking for work as in the past.

Many among this new group have pending asylum cases. They shouldn’t be considered undocumented unless a judge decides they’re not eligible to stay permanently. Subtract them from the number of apprehensions, and the total looks much smaller.

Many are deported

The crisis at the border is not really a numbers crisis. It’s a bureaucratic emergency because the United States has failed to adapt to the shift in immigration flows from Mexican men seeking work to Central Americans seeking asylum.

Unlike Mexican men, whom it could quickly deport, it is obligated by law to give those who fear going back to their country a day in court. It’s a much longer, back-office-heavy process that immigration authorities are ill-equipped to do. For years, they’ve directed much of their funding towards border agents and fences. That’s why they’re struggling now, even though the number of immigrants is significantly smaller than what they handled in the past.

Even taking into account that mismatch, the US deports thousands of immigrants every year.

That’s another group of people that should be removed from Trump’s tally of undocumented immigrants.

Border crossers vs. residents

Even after those adjustments, apprehensions are not the best statistic to look at if what’s worrying Trump are undocumented immigrants. (Those who are caught and have no permission to be in the United States will be deported. As we said above, asylum seekers are allowed to stay.)

He should instead focus on people who live in the United States without permission. That number has come down from a pre-Great Recession peak of more than 12 million to less than 11 million in 2016, according to analysis by the Pew Research Center.


Again, the drop in the number of Mexican immigrants coming to the United States is partly behind that math. In addition, many immigrants are leaving, whether through deportation or on their own. Add to that the number of undocumented residents who die and those who get papers to legally live in the county, and you get more immigrant residents exiting the undocumented column than entering it.

Data from the Center for Migration Studies show that’s been the case in recent years:

Most don’t enter illegally

Of the undocumented population living in the United States, not all entered illegally. In recent years, more than half of the people settling in the country without permission entered on a visa and overstayed it. “It’s hard to walk here from India,” said Jeffrey Passel, senior demographer at Pew.


While many asylum seekers show up in the apprehension figures, visa overstayers don’t at all. That’s another reason why the number of people border patrol agents catch shouldn’t drive the immigration debate.

Does the border crisis change the math?

Immigration hawks fear that the asylum seekers showing up at the border will eventually become undocumented immigrants. US authorities have been releasing many of the new arrivals because there’s not enough detention space. And there are rules that limit how long officials can keep immigrant children in custody. 

Immigration statistics lag, so we won’t know for a while how many of those people end up living in the United States illegally. Robert Warren, a senior visiting fellow at the Center for Migration Studies, doesn’t believe they’ll make much of a difference given recent trends. The potential impact of border crossers has shrunk along with their share of the undocumented population.

A look at border crossers who were caught and those who settled in the United States sheds some light on what we might see. The number of immigrants requesting asylum started to swell a few years before Trump took office, and so did the number of apprehensions. The number of undocumented immigrant residents who entered the country illegally went up too, but remained well below apprehensions. 

That’s not to say Trump should discard apprehension statistics. He just needs to work on the takeaway. Apprehensions don’t equal undocumented immigrants. What they’re showing these days is that the asylum system is clogged up. That’s keeping the United States from protecting Central Americans at risk, and encouraging more of them to come.

“It is a very serious situation when you have so many families and children coming up to apply for asylum,” Warren said. “The thing that might be getting missed is we haven’t set up our capacity to handle that situation.”