“Oh boy,” Donald Trump exclaimed on the campaign trail last summer, as he hoisted a colorful poster aloft for a cheering audience in Fort Lauderdale. “You’re not going to be happy with this!” The poster showed soaring immigration numbers, highlighted in bright blood-red—a menace streaming unchecked into America.

Those numbers were cooked up at the Center for Immigration Studies, a small advocacy operation in Washington that emerged, early on in the campaign, as Trump’s go-to source for research about migrants and the dangers they pose. Trump repeatedly cited CIS studies in his TV ads and speeches, tweeted links to the group’s research, and used its data to argue that immigrants are “bringing drugs” and “bringing crime” into the United States. After he implemented his controversial Muslim ban, CIS provided Trump with much-needed political cover: Media outlets from NPR to The Washington Post quoted the center’s experts defending the policy. Most, in fact, portrayed CIS as a respectable research institute—after all, the group boasts that its board of directors includes a mix of “active and retired university professors” and “civil rights leaders.”

CIS, however, is far from a reputable scholarly organization. It’s a far-right fringe group that was founded on disturbing and discredited ideas about racial inferiority. Today, CIS churns out doctored “studies” that portray an America under siege from immigrants pouring over our borders, destroying our environment, and draining our coffers.

The group was the brainchild of John Tanton, a Michigan ophthalmologist who developed an interest in eugenics after hearing about “a local pair of sisters who have nine illegitimate children between them,” as he wrote in 1969. He believed in the debunked theories of Thomas Malthus, a nineteenth-century British cleric and scholar who warned that the world would run out of resources if the population were allowed to grow unchecked. For Tanton, “overpopulation” meant people of color. To prevent nonwhites from procreating, he endorsed birth control in the United States and sterilization efforts in Africa. And to block what he called a “Latin onslaught” of immigration that threatened to subsume Western culture, Tanton founded or funded 13 think tanks and advocacy groups—a constellation of far-right organizations that form the core of the modern movement to limit immigration into the United States.

CIS, which Tanton founded in 1985, was specifically designed to give the nativist movement a semblance of legitimacy. According to a letter buried deep in the bowels of the Bentley Historical Library in Ann Arbor, in one of 14 boxes of his correspondence open to researchers, Tanton imagined “a small think tank” that would be deployed to “wage the war of ideas.” As a serious organization with a respectable-sounding name, it would create policy briefs for conservative candidates and members of Congress—and provide cover for the lobbying efforts of its rabidly xenophobic sister organization, the Federation for American Immigration Reform, founded in 1979.