Most Americans still support a heavy hand on illegal immigration. Almost nine out of 10 Republicans and independents who lean Republican say they want a strong military presence on the border, according to recent Pew polling, with a large majority also supporting stricter entry controls such as allowing immigration officers to review social media accounts. 

But 17 months into Trump’s sweeping immigration crackdown, which has so far removed over a million people from the labor force, views among independents have rapidly soured. And in addition to Trump’s hardline approach that has alienated voters, the economic costs of the president’s policies are starting to become clear as well. Immigrants were a crucial component of the U.S. economy, and as it turns out, immigrant labor was also central to many people’s hopes of staying in a job.

Many workers who were born in the U.S. benefited from a complementary immigrant workforce that supported parts of their industry, according to a study by researchers at the University of Colorado Boulder and published last week by the National Bureau of Economic Research. But with the Trump administration’s immigration crackdown over the past year, largely mediated through ICE, at least 1.2 million foreign-born workers have left the labor force, dismantling the structure that supported native-born jobs too.

“Heightened ICE activity is harming the labor market overall, and we find no evidence that it is benefiting U.S.-born workers,” Chloe East, one of the study’s authors, said in a statement. “If anything, job opportunities for U.S.-born workers are going down as a result.”

A chilling effect on jobs

Labor economics isn’t known for having the most accessible lexicon. Phrases like “human capital” and “skills gap” can have a variety of interpretations depending on the context. Complementarity is another vague, nondescript term in the field, but for all its characterlessness, it might just describe one of the most prominent forces in today’s labor market.

Few things in economics happen in isolation, and complementarity occurs when one piece of the economic puzzle functions better or more productively when paired with another input. Workers are a clear winner thanks to this economic rule, with most employees benefiting enormously when others, such as immigrants, are allowed to participate in the workforce. The catch with complementarity, however, is that its effect is most noticeable when one part of the pairing gets stripped away.

The researchers behind the recent study crunched national labor market and ICE arrests data from the past year, a period during which daily apprehensions by ICE surged from around 300 to nearly 1,300. The authors then compared labor effects in areas with large upticks in arrest with comparatively stable ones to see how total employment changed in places where the foreign-born workforce suddenly shrunk or vanished. The study focused its findings on male workers, who are demographically more likely to be affected by immigration enforcement.

The authors found that in an average area that saw a surge in ICE activity, 7,574 likely undocumented male workers stopped working, coming out to around six males leaving the workforce for every ICE arrest, primarily out of fear of being arrested themselves. 

“Chilling effects capture the fact that heightened ICE activity may cause people to be fearful of participating in their regular activities—including going to work,” the study’s authors wrote.

At the same time, because of complementarity, U.S.-born males with a comparable education level and who work in sectors reliant on immigrant labor, such as construction or agriculture, also dropped out of the workforce in greater numbers. In an average high-enforcement area, the number of U.S.-born male workers fell by 1,200, the authors found, coming out to approximately one job loss for every six likely undocumented workers who left the labor force.

“This is consistent with a model where undocumented immigrants and U.S.-born workers are complements, rather than substitutes for each other in the labor market,” the researchers said.

In sectors such as construction, where the share of immigrant workers is high, U.S.-born workers often take up roles that depend on work provided by foreign-born counterparts, such as manual labor. Without immigrant workers, the business model foundation crumbles, and the industry at large has to scale back or shut down, reducing demand for U.S.-born work in the process.

That immigrant labor is a complement instead of a replacement for native-born work is already known. A report published last year by the Penn Wharton Budget Model found that even high-skilled workers—which tend to be native-born—are affected by mass deportations and the removal of undocumented workers from the labor force. Depending on the scale of deportations, high-skilled workers could see their wages fall up to 2.8% over the next 30 years relative to a scenario without an immigration crackdown, the report found.

Bad for both

The Trump administration has framed its immigration enforcement agenda in part as a means to increase the number of jobs available to U.S.-born workers. But in practice, the complementary jobs immigrants tend to perform—which tend to be low-wage and physically demanding—are not the kind native-born workers are eager to replace. The latest study found “no evidence” that job opportunities had increased in immigrant-heavy sectors, nor that employers were raising wages in a bid to attract more U.S.-born workers.

The more realistic outcome is what businesses usually do when a labor supply dries up: Scale back their operations. 

The construction industry is already a strong case in point, as East’s study found that the employment rate for U.S.-born workers in construction has dipped 3% due to ICE activity. Last year, almost half of construction firms attributed project delays to labor shortages, according to a survey by the Associated General Contractors of America, a trade association. Nearly 30% of firms said the administration’s immigration enforcement had contributed to their staffing woes.

“There is a common narrative out there that mass deportations will free up job opportunities for U.S.-born workers, but numerous studies, including ours, have shown that is false,” said East, the study’s author. “If a construction company can’t find laborers, they’re going to take on less work and hire fewer people overall.”