President Donald Trump has big, terrific plans to make America great again, just as soon as he finishes watching multiple hours of Fox News ever day and finding out the secret ingredient in Mar-a-Lago’s “beautiful” chocolate cake. One way he plans to restore greatness to America, a country founded by immigrants, is to kick out as many undocumented people as is logistically possible.

The decision by the Trump administration in February to set the stage for a massive immigration crackdown—expanding the powers of federal agents, calling for local law enforcement to get involved in the effort, and widening the definition of “removable alien”—has already taken an incredible human toll. Sara Beltran Hernandez, a mother of two who was reportedly the victim of domestic abuse in El Salvador, was removed from a Texas hospital bed—where Beltran Hernandez says she was being treated for a brain tumor—and taken to the Prairieland Detention Center (she was later released and is being allowed to live with family in New York while her asylum claim is processed). Last week, Roberto Beristain, a restaurant owner living in Indiana for 20 years who received permission from the Obama administration in 2012 to stay in the country as long as he periodically checked in with immigration officials, was deported to Mexico. The pages of countless newspapers across the country are filled with similar stories.

But the president’s anti-immigration policies also present a major risk to several U.S. economic sectors that rely on immigrant labor, a fact that Trump—as a businessman who routinely hires seasonal immigrant laborers at his hotels and golf courses and winery, and employed undocumented workers to build Trump Tower—ought to understand better than anybody. Nevertheless, 1,470 economists have decided to give the president a refresher on the importance of immigration in the form of a very public letter. Per CNN Money:

In a letter to President Trump and top Congressional leaders Wednesday, nearly 1,500 economists extolled the economic benefits immigrants bring to the U.S. and urged Congress to "modernize" the country's immigration system.

“[I]mmigration is one of America's significant competitive advantages in the global economy,” the letter said. “With the proper and necessary safeguards in place, immigration represents an opportunity rather than a threat to our economy and to American workers.”