Since his debut on the political stage, Donald Trump has unceasingly pledgedto construct a “big, beautiful wall” on the United States’ southern border, believing it would provide an immediate solution to the dilemma of undocumented immigration from Mexico. Toward that end, President Trump has forced a partial government shutdown and Tuesday night sought to persuade the public of the wall’s necessity.

The border wall is unambiguously intended to keep Mexicans out of America. But if Trump wants to stem migration from Mexico, he should also consider keeping Americans out of Mexico.

I’m not thinking of the American retirees, honeymooners or spring-breakers who visit Mexico every year, although these folks undeniably number in the millions. I’m thinking instead of the far more powerful representatives of American business, government and philanthropy who have played a pivotal role in transforming Mexico during the past century, particularly by decimating Mexico’s rural economy — and thereby doing a great deal to stimulate emigration to the United States.

Trump’s plan for the wall has said nothing about this southbound traffic. Yet, as more than 100 years of history reveals, that American involvement in Mexico has played a vital role in spurring northward migration.

In the late 1800s, profit-seeking U.S. businessmen swarmed into Mexico, welcomed by the pro-American dictator Porfirio Díaz. U.S. investors bought up plantations, ranches, oil fields and railroads, and by the turn of the 20th century, they controlled vast swaths of the Mexican economy. Such American domination sowed bitterness among Mexicans and ultimately helped spark the Mexican Revolution of 1910-1917.