Just over 10 years ago, United States Border Patrol agents were startled by an unexpected new development in their rear-guard battle to stop illegal immigration: Brazilians.
In 2005 thousands of them started streaming across the southwestern border. More than 31,000 were apprehended by the Border Patrol trying to make their way into the United States, a number surpassed only by Mexicans, Salvadorans and Hondurans.
And then, just as abruptly, the flow stopped. Under pressure from Washington, Mexico reimposed a tourist visa requirement on Brazil that it had eliminated five years before. This severed a trafficking route that started with an easy flight from Rio de Janeiro to Cancún and ended in a trek across the desert into southern Texas.
In 2006, apprehensions of Brazilians by the Border Patrol fell 95 percent, to 1,460. Today few even try to sneak through. Over the last three years it has been mostly Guatemalans, Hondurans and Salvadorans who are fleeing home by the tens of thousands, hoping to cross Mexico to reach the United States.
But as in 2005, the main buffer the United States has to stop Central American immigrants from entering illegally across the border — its wall, as it were — is Mexico. Mexico is a tool that the Trump administration now stands to lose.
Ever since the skirmishing of the first few days of Donald J. Trump’s presidency, when President Enrique Peña Nieto of Mexico canceled a visit to the United States after Mr. Trump repeated that Mexico would pay for his promised border wall, Mexican officials have hoped that more serene heads in the administration might moderate some of Mr. Trump’s more hostile proposals.
Mexico’s development strategy over the last three decades has been all about tying its economy with that of the United States. The North American Free Trade Agreement was supposed to be its growth engine, drawing investment by multinational companies to serve the enormous American market. Immigration north served as its pressure valve — allowing it to weather repeated financial crises by allowing the American job market to absorb idle Mexican workers. Not incidentally, that also contributes to United States economic growth.
As I noted in a column last month, with President Trump promising to turn his back on the United States’ southern neighbor — renegotiating Nafta on presumably worse terms for Mexico and walling off the southwestern border — Mexican officials are desperately trying to convince his administration that the United States needs Mexico, too.
Their hopes, however, are likely to be dashed. This week, Secretary of State Rex W. Tillerson and his Homeland Security counterpart, John F. Kelly, are visiting Mexico to assess what sort of bilateral cooperation might be possible in this new era. Even before they got on the plane, new rules suggest that the hard line will prevail.
Two memos signed by Mr. Kelly — guidelines for Mr. Trump’s promised immigration crackdown — call for aggressively seeking out, detaining and deporting immigrants living without authorization in the United States. They order the hiring of 10,000 immigration enforcement agents and 5,000 Border Patrol officers, and direct Customs and Border Protection to start designing and building the wall.
And in a move sure to stir Mexican outrage, the guidelines direct immigration officials to return immigrants from any country caught entering illegally to “the territory of the foreign contiguous country from which they arrived” while they await removal proceedings in the United States. And that means Mexico.
Officials at the Department of Homeland Security argued that returning Central Americans to Mexico would be done only in a limited fashion, and only after discussions with the government of Mexico. Somehow, it seems unlikely that a provision designed to reduce costs for the American government by foisting them onto Mexico will go down well in Mexico City.
“That would violate every agreement and convention,” said Gustavo Mohar, who formerly served as Mexico’s top negotiator for immigration with the United States, about the provision.
“Mexico is obliged to receive Mexicans, but it has the right to demand accreditation that they are indeed Mexican,” Mr. Mohar said.
What might Mexico do in return? Refuse to take people who can’t prove Mexican citizenship? As a former foreign minister, Jorge Castañeda, told me, one option might be to get out of the way and let Central Americans cross Mexico unimpeded to the United States.
Here’s what is at stake. Last year, Mexico returned 143,057 Central American migrants to their countries of origin. It sent home more than 59,000 Guatemalan migrants moving north across its territory, and repatriated nearly 48,000 Hondurans and 31,000 Salvadorans, according to the International Organization for Migration.
Over all, Mexico stopped and sent back almost twice as many Central Americans as the United States did. The question is, Could President Trump’s wall replace this buffer?
History suggests the most productive policy would aim to manage immigration from poorer countries to ensure it remains legal. Trying to stop it simply pushes it underground. An immigrant guest-worker program managed by Mexico and the United States, some experts suggest, could help migrants, protect American workers and fulfill the needs of American employers.
But even if such enlightened policy is still politically out of reach, the argument for cooperation between Mexico and the United States remains powerful. These days, illegal migration from Mexico is a relatively minor problem. Apprehensions of Mexican immigrants at the border are running at their lowest since the 1970s. Fewer Mexicans are coming north across the border than are returning home from the United States. Last year, more Central Americans than Mexicans were apprehended by the Border Patrol. Mexico is now mainly a passageway.
Past American governments have recognized the importance of Mexico’s help. Washington has given Mexico $24 million to support immigration enforcement — mostly in training and high-tech gadgetry — and obligated $75 million more.
Of course, Mexico doesn’t do this only out of love for its northern neighbor. As Mr. Mohar points out, even if their final destination is the United States, tens of thousands of Central Americans marching northward can put stress on Mexican communities, too. Notably, if Mexican officials were to just wave them through, they would place enormous strains on cities along Mexico’s northern border.
And yet the new American administration might recognize that preventing Central Americans from reaching the United States imposes a high political cost on the Mexican government. In 2014, when Mr. Peña Nieto announced the Southern Border Plan to tighten security around border points of entry and known migration corridors, he was harshly criticized for doing dirty work for the United States.
“It became a news story in Mexico: Why are we treating Central American migrants like the United States treats Mexicans?” said Andrew Selee, executive vice president of the Wilson Center in Washington, a research center focused on international affairs.
“The Mexican government persisted because it perceived that a migration crisis on the border with the United States could also damage Mexico,” he noted. “There were other things at stake in the relationship that it didn’t want to risk.”
By threatening to build a wall and leave Nafta and do any number of things to Mexico, Mr. Trump is changing this equation. If hostility is all he has to offer, the political cost for Mexico to be America’s wall may prove too steep.
Eduardo Porter writes about business, economics, and many other matters as a member of the New York Times editorial board.