On Monday, the night before the formal launch of his reelection campaign in Florida, President Donald Trump issued a warning. “Next week ICE will begin the process of removing the millions of illegal aliens who have illicitly found their way into the United States,” he tweeted. “They will be removed as fast as they come in.”

This is a lie. Despite Trump’s obsession, mass deportation of millions of undocumented immigrants from the United States is virtually impossible. Estimates suggest that the cost of detaining, processing, and physically removing the country’s 11 million undocumented immigrants would be astronomical. The country’s immigration system isn’t capable of such punitive expediency, either. The Washington Post’s Nick Miroff did the math: At its current rate of 7,000 monthly deportations, it would take two and a half decades for Immigration and Customs Enforcement to reach Trump’s punitive threshold.

But since the president likes to deal in fantasy, let’s indulge him: What if Trump had a Thanos-like gauntlet that could make America’s undocumented community instantly disappear? The consequences for the country’s economy would be dire and immediate.

According to a study by New American Economy, a bipartisan research group, businesses owned by immigrants in general employ more than 8 million Americans and add $1 trillion to the economy. Almost 750,000 of those entrepreneurs are undocumented. Numerous specific industries would be affected by the disappearance or severe reduction of the immigrant workforce. The restaurant and hospitality industry would be in serious trouble: a fifth of the country’s cooks and 24 percent of maids and housecleaners are undocumented. So are 22 percent of construction workers, so building across the country would likely grind to a halt. Good luck with the next infrastructure week.

Still, no areas of the American economy would face worse disruption than the farming, meat, and dairy industries. Thirty-six percent of all agricultural workers are undocumented.

For pig farmers in Iowa, a state Trump won in 2016, the absence of immigrant workers would present a daunting challenge. “Iowa dominates the U.S. pork industry,” professor Dermot Hayes, of Iowa State University, told me in a recent interview. “At the labor level—the people who actually perform the work—I would guess at least 80 percent of them are immigrants.” For years now, Hayes says, immigrants have taken on “very tough jobs, very demanding, in circumstances that are harsh. These are people who are so hungry for work that they are willing to do what other people would prefer not to do.”

Others agree. Based in Washington, the North American Meat Institute is the country’s largest association of meat industry companies. Sarah Little, the group’s vice president of communications, told me the significance of immigrant labor in Iowa is part of a larger and far-older trend in the industry. “Historically, immigrants to America work in meatpacking plants. It’s been that way for over a hundred years,” she said. Little warned that a sudden decrease in this labor pool would have an abrupt negative impact on Iowa’s pork industry. “It would be problematic,” she said. “They wouldn’t be able to manufacture at the pace that they do.” That’s an understatement. According to Dermot Hayes, such a reduction in the immigrant workforce would lead to a multitude of painful challenges. “There would be no place to process the animals. The plants would have to close until they restructured. There would be severe animal welfare concerns all over Iowa,” Hayes said.

For those actually in the field, the need for immigrants in Iowa’s pork industry is not up for debate. Pork farmer David Walter, who operates a small meat locker in Corning, Iowa, told me that immigrants “do the work in situations for which we can’t find a lot of other help in this industry. It’s hard, continuous labor.” As a matter of fact, Walter hopes for the exact opposite of Trump’s crackdown. “I’d like to have some around here,” he acknowledged, candidly. “I’m having a hard time finding help, but there’s no immigrants in my area. I could hire a couple of them full time. I’m small. I could get a little bigger. If I had a couple of guys full time, I could do more.”

“Eighty percent of the milk in Wisconsin is harvested by immigrants. If you took the immigrants away way over half of the farms would go out of business.” — John Rosenow, dairy farmer

In 2016, Trump narrowly edged out Hillary Clinton in Wisconsin. For the state’s dairy farmers, a radical decline in immigrant labor would be a disaster. Shelly Mayer of the local Professional Dairy Producers association, a professional development organization that helps the state’s farmers. In an interview, Mayer explained that Wisconsin farms are facing a crisis as the region’s population declines. “One of the biggest challenges that we have is the absence of rural labor,” she told me. “There’s fewer people living in these rural communities so the workforce that we naturally used to have 30 years ago isn’t around.” Immigrant labor has helped Wisconsin’s dairy farming thrive by filling the gap. Immigrants have “become an important part of the fabric of the dairy industry,” Mayer told me. “They have the ambition and accountability to be with us at our side and show up to work every single day.” If Trump had his way and immigrant workers vanished from Wisconsin, the industry would encounter exceptional challenges. “We would become even more depleted of having the folks that are the sort of hands who are going to show up to milk the cows, feed the calves, maybe mix the feed,” she said.

In many cases, Wisconsin farmers have built deep bonds with the immigrant community that works in the local dairy industry. “You think of some of those folks who have been here maybe as long as 20 years who are extremely skilled,” Mayer told me. “They have proven that they love what they do. We have put a lot of training into them. It would be devastating to lose good quality people.”

John Rosenow knows this well. Rosenow owns Rosenholm dairy in Cochrane, 10 miles from the Mississippi River, in western Wisconsin. He’s certain that a potential shortage of immigrant farm workers would cripple the state’s economy. “Our industry doesn’t exist without immigrant labor,” he told me. “Eighty percent of the milk in Wisconsin is harvested by immigrants. If you took the immigrants away, way over half of the farms would go out of business.” Rosenow has established deep bonds with a number of immigrant families from Veracruz, Mexico. “We have members from three different families, and they have been providing us with labor for 20 years now,” he said. “They are highly skilled. They know how to do everything.”

After decades of working alongside immigrants, Rosenow has learned to admire their discipline. “If you’re a dairy farmer, you have a certain kind of work ethic,” he told me. “I work a lot. All the time. They have the same thing.” When I asked him what would happen if Trump’s allegedly massive raids reached Wisconsin and swept away many of the immigrants who work in the state’s dairy industry, Rosenow didn’t hesitate. “Within days there wouldn’t be any milk on the shelves,” he assured me. “There would be no people to milk the cows. A lot of the cows would go to slaughter and the industry would downsize by at least 50 percent. There would be a shortage of milk, cheese, and butter within maybe a week.”

Before we hung up, Rosenow told me a story. A few years back, he joined a local nonprofit called “Puentes/Bridges.” Over the decade and a half, the organization has taken Wisconsin farmers to the villages and small towns in Mexico that were once the homes of the immigrants who now work in their farms. “I’ve been to Mexico nine or 10 times to visit their families and their villages in the state of Veracruz,” Rosenow told me. “I go to Mexico because I need to know where they come from, why they come here, what their families are like, what the draw is to come to our place. But also what they’re leaving behind.”

What he saw in the villages around Orizaba changed his perspective. It also touched his heart. In a recent trip, as he drank coffee and chatted amicably, he saw a young boy walking around, hiding behind his mother’s skirt. Someone called the boy over and introduced him to the tall Wisconsin farmer. His name was John. “They named him after me,” Rosenow told me. “That was just about more than I could handle.”