President-elect Donald Trump intends to pursue a hard-line policy on undocumented workers, deporting millions in what he has billed as the “largest deportation” in the nation’s history.

The inspiration for this plan is the appallingly named Eisenhower-era program “Operation Wetback,” which relied on mass raids and roundups to deport more than a million individuals to Mexico in 1954. No surprise that Trump, who speaks regularly of an “invasion” of undocumented workers, is drawn to this model of a military-style operation.

What he doesn’t grasp is that the relative success of this earlier expulsion rested on a long-standing tradition of close coordination with the Mexican government — even its active support and cooperation. It’s a lesson that Trump, who likes to make a virtue of going it alone, ignores at his peril.

The history of attempts to fight the flood of undocumented workers from Mexico begins not with the U.S., but with Mexico itself. As the historian Kelly Lytle Hernández has noted, Mexico actively sought to discourage its citizens from emigrating to the United States for much of its modern history.

This was a priority of Porfirio Díaz, who served as Mexico’s president throughout much of the late 19th and early 20th centuries. Díaz, who sought to modernize his nation’s economy, didn’t want to lose workers to the U.S. when the country needed them at home.

Unfortunately for Mexico, the farms and factories across the border typically paid better, and many Mexicans moved north, living as undocumented workers. Though this exodus stalled during the Great Depression, the labor shortages of World War II sparked another wave of emigration.

While some of these workers assumed legal employment in the U.S. via the so-called Bracero Program, illegal immigration continued apace. Either way, business interests in Mexico protested the loss of able-bodied workers. Mexican landowners were particularly vocal: With no one to pick them, crops like cotton often rotted in the fields.

In response, the Mexican government criminalized unsanctioned migration. It also called on its northern neighbor to do more to help. In 1943, for example, Mexican diplomats wrote the U.S. State Department, demanding that the country crack down on illegal immigration. The country repeatedly requested that Congress pass laws making it felony to knowingly hire undocumented workers. (Agribusiness interests, who relied on the cheap labor, thwarted this legislation.)

By the end of World War II, the two nations began building a collaborative system of deportation to address these concerns. The U.S. focused on rounding up and shipping undocumented migrants to the border, where they would be handed over to Mexican officials.

In building a cooperative deportation system, the two nations jointly prosecuted what Hernández calls the “symbiotic crimes of unsanctioned emigration and undocumented immigration.”

Neither country treated the migrants gently. While violations of civil liberties were commonplace north of the border, the migrants didn’t fare much better at the hands of the Mexican government. As one U.S. Border Patrol agent noted, upon being marched back into Mexico, “the (deportees) are sometimes dealt with rather harshly by the (Mexican) authorities,” enduring beatings and other punishments.

No less problematic was the fate of the migrants. Rather than being sent back to their homes, most would be placed under armed guard, put on buses and trains, and then shipped to parts of the country in need of cheap labor.

By the 1950s, the scale of the border crossings began to attract negative attention in the U.S., with the now-familiar language of “invasion” and “flood” used to describe the issue. This nativist sentiment combined with that era’s Red Scare to fuel fears that Communists might be crossing the border, too.

In 1954, President Dwight Eisenhower appointed General Joseph Swing to head the Immigration and Naturalization Service and address the issue. Swing and his deputies began working closely with the Mexican government to plan the mass deportation eventually known as Operation Wetback. The two countries coordinated on the movement of deportees via train to the Mexican countryside.

When the raids began, though, the role of the Mexican government in facilitating what became the largest mass deportation in the nation’s history was invisible to most Americans. Instead, carefully staged images of U.S. law enforcement rounding up undocumented workers dominated coverage. What happened after the deportees crossed the border rarely came up.

Now Trump wants to repeat this feat. That won’t happen, though, unless Mexico cooperates. There are increasing signs that it will not. After Trump’s election, Mexican President Claudia Sheinbaum declared: “We don’t agree that migrants be treated as criminals.” And when Trump floated the idea of slapping Mexico with 25% tariffs until border crossings end, the nation threatened to hit back with tariffs of its own.

More generally, the entire landscape of migration has changed in recent decades. The people crossing the border now are not exclusively — or even primarily — from Mexico; they’re from countries elsewhere in Latin America. And relations with those nations are even more vexed.

For example, when Trump recently vowed to move forward with his plan to expel undocumented workers, the president of Honduras threatened to retaliate by evicting the U.S. military from the major base it operates in the country.

The deteriorating relations between the U.S. and its neighbors do not bode well for Trump’s efforts. He may soon learn that deportation requires more than coercion; it requires cooperation, too.

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This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

Stephen Mihm, a professor of history at the University of Georgia, is coauthor of “Crisis Economics: A Crash Course in the Future of Finance.”

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