Justin Fox

In March 2021, two months after she and President Joe Biden took office, Vice President Kamala Harris was assigned the task of addressing the "root causes” of illegal immigration from the Central American countries of El Salvador, Guatemala and Honduras, aka the Northern Triangle. This is the job that some journalists and administration critics at the time dubbed "border czar.” That greatly overstated Harris’ role, but hey, if things had stayed quiet along the U.S.-Mexico border over the past three-plus years, she’d probably be calling herself that, too.

Instead, it’s Republicans who keep using the term, for obvious reasons. The number of "Southwest border encounters” — people who are apprehended or turn themselves in to authorities after illegally crossing over from Mexico — hit new highs in 2022 and 2023 before starting to decline early this year.

But what about illegal immigration from El Salvador, Guatemala and Honduras, the phenomenon that Harris was supposed to address? Border encounters with citizens of those countries are up a lot from the lows of 2020, when the Covid-19 pandemic temporarily put a halt to immigration of all kinds. But the trend since March 2021 is downward, and even the monthly peaks of 2021 did not surpass that of May 2019, when Donald Trump was president.

So the vice president does not appear to have failed in her limited assignment. Whether she succeeded is more difficult to say.

For one thing, border encounters aren’t a perfect measure of illegal immigration. From March 2020 to May 2023, for example, the emergency COVID-19 health order known as Title 42 allowed border agents to return almost every illegal entrant they encountered to Mexico, leading many would-be immigrants to try again and again, resulting in individuals being counted multiple times in the encounter statistics before May 2023. The numbers also don’t count border-crossers who elude the authorities, and as I wrote in March there were probably more of them before May 2023 than after (not to mention many more in the 1990s and 2000s than in recent years).

Put it all together, and I’d conclude that illegal immigration from the Northern Triangle has probably declined since March 2021 even if it didn’t follow the exact trajectory shown in the above chart. There definitely has been a sharp decline in the region’s share of total illegal immigration to the U.S., from more than 70% of border encounters in the spring of 2019 to 49% in March 2021 to below 20% lately.

Why the decline? I don’t think it can be chalked up to that June 2021 speech in Guatemala when Harris instructed would-be immigrants, "Do not come. Do not come.” Also, because I’m sure some readers will wonder about this, Nayib Bukele’s attention-getting tenure as El Salvador’s president doesn’t seem to explain much of the drop, either. El Salvador led the way in Northern Triangle immigration to the U.S. for decades, but it had fallen behind Guatemala in border encounters by the mid-2010s and slid into last place among the three countries in the 2018 fiscal year — before Bukele took office in June 2019. It hasn’t budged from that spot since.

I do believe the answer has something to do with the relatively strong recent economic performance of the Northern Triangle countries. Faster economic growth presumably means more opportunities at home and fewer reasons to leave.

What drove this outperformance? The various aid initiatives under the banner of Harris’ "Root Causes Strategy,” with a total price tag of $4 billion over four years, may have helped. They have been dwarfed in scale, though, by the $15.1 billion increase between 2019 and 2023 (from $21.7 billion to $36.8 billion) in the annual flow of remittances into the three countries. More than 90% of that money came from Salvadorans, Guatemalans and Hondurans working in the U.S., where big pay gains at the bottom of the wage scale as the economy recovered from the Covid-19 pandemic delivered outsized benefits to recent immigrants. Remittances now amount to about a quarter of gross domestic product in Honduras and El Salvador, and nearly 20% in Guatemala.

The theory I’m proposing here, then, is that a big increase in money sent home by Northern Triangle immigrants now in the U.S. (both legally and illegally) has led to a slowing of illegal immigration from the Northern Triangle. The secret to reducing illegal immigration now, you see, is allowing more of it in the past.

And yes, put that way it sounds pretty ridiculous. But it gets at the complexity inherent in trying to address the root causes of illegal immigration. One important root cause that doesn’t receive enough attention is the state of the U.S. economy — in a recent Center for Global Development working paper, economist Dany Bahar found a strong positive relationship over the past quarter century between Southwest border encounters and U.S. labor market tightness, measured as the ratio of job openings to unemployed. Border encounters plummeted during and after the Great Recession, and estimates of the illegal-immigrant population based on Census data showed a decline of 2 million between 2007 and 2019. Illegal immigration began to rise again as labor markets tightened in 2018 and 2019, then took off in 2021 as the U.S. economy roared back from COVID-19 shutdowns.

In the Northern Triangle countries, the economic boost at home delivered by the gusher of remittances from the U.S. seems to have counteracted the pull of job opportunities in the U.S., for now. But illegal immigration from Mexico — where the remittance flow is nearly twice as big in dollar terms as that to the Northern Triangle, but much smaller as a share of GDP — is up sharply from pre-pandemic levels. And the majority of border encounters since mid-2022 have been with citizens of countries other than Mexico, El Salvador, Guatemala and Honduras, a development that the Biden administration almost certainly did not anticipate in March 2021.

In other words, there’s nothing wrong with trying to address the root causes of illegal immigration in other countries. Just don’t expect your efforts to actually reduce illegal immigration overall.

(Justin Fox is a Bloomberg Opinion columnist covering business, economics and other topics involving charts.)