“It’s causing a lot of panic,” said Oscar Renteria, the owner of Renteria Vineyard Management, which employs about 180 farmworkers who are now pruning grapevines in the Napa Valley.
When word of the raids spread, he received a frenzy of emails from his supervisors asking him what to do if immigration officers showed up at the fields. One sent a notice to farmhands warning them to stay away from 7-Eleven stores in the area.
“Our work force frequently visits 7-Elevens,” said Mr. Renteria. “They’re very nervous. It’s another form of reminding them that they’re not welcome.”
The Obama administration largely took a lower-profile approach to enforcement, auditing employers’ compliance in documenting their workers’ status without conducting many on-site investigations. A handful of employers faced prominent criminal cases in recent years, but most companies employing workers illegally avoid serious charges, because it is often impossible to prove that they knew someone had handed in fake documents.
“The consequences are not that harsh, and the effect of the enforcement is less than it should be,” said Jessica M. Vaughan, the director of policy studies for the Center for Immigration Studies, which advocates tighter restrictions on immigration.
The law requires employers only to ensure that documents appear to be valid, and federal law prohibits them from requiring specific types of identification from workers.
Credit Max Whittaker for The New York Times
Employers negotiate reduced administrative fines and sometimes put political pressure on local officials when they become targets, making the punishment for companies “weaker than it should be,” Ms. Vaughan said. “There are employers for whom the penalties are just the cost of doing business.”
The more lasting effect of raids is to spread fear among undocumented workers, who often end up bearing the brunt of enforcement action at the workplace.
“Having some semblance of a fear of workers’ being arrested will have a behavioral shift,” said William Riley, who spent 20 years as an ICE special agent, under both Bush presidencies and the Clinton and Obama administrations, and is now a consultant at Guidepost Solutions, working on corporate compliance. Mr. Riley said that under the last administration, people were more lax about working illegally, assuming they wouldn’t be arrested.
“There was slightly more complacency when it was pretty well known that there wasn’t a fear of being arrested in your workplace,” Mr. Riley said, nor much of a deterrent to “using fake documents to get a job.”
Mr. Renteria said he expected raids on farms soon, because the industry is a big employer of “people with complicated immigration status.” More than half of California’s agriculture workers lack documents, according to a federal survey. Mr. Renteria worries that if agents home in on the Napa area, no one will stay to harvest the grapes.
“They will start calling their cousins, aunts and uncles and finding the safest place where the work is,” he said.
The last flurry of public, on-site investigations happened under President George W. Bush, who sent immigration agents to several meatpacking plants and other workplaces. Those raids led to hundreds of arrests of workers and prompted many other employees to stop reporting to work, according to local news reports. But they also enraged advocates for immigrants and drew complaints from business owners.
The Obama administration changed tack and pursued employers mainly by inspecting their paperwork. Such audits doubled from fiscal years 2009 to 2013, reaching 3,127, then declined sharply.
Law enforcement may welcome a more aggressive approach under the new administration. But sending armed agents to the doorsteps of American companies could prove politically uncomfortable for Mr. Trump, who has portrayed himself as an ally to business.
Doris Meissner learned how quickly local politicians can spring into action when their hometown industries feel threatened. As head of the agency that preceded ICE, the Immigration and Naturalization Service, from 1993 to 2000, Ms. Meissner tried to focus on holding employers accountable.
She approved the start of Operation Vanguard in the 1990s, in which the agency asked for employee records in several Nebraska meatpacking plants. When it came time to pursue charges against some employers, Ms. Meissner said, she started receiving frantic calls from Nebraskans on Capitol Hill.
“The politics gets hot and heavy,” Ms. Meissner said. “These are communities that are heavily reliant on these industries. This is the major employer. These are the major consumers at the stores and the bowling alleys.”
Audits of employers were favored early in the Obama administration as an immigration enforcement tool, but their use then declined.
Ms. Meissner says work-site raids don’t work in the long term because they fail to address the real magnet drawing people into the country: a need for laborers.
Cracking down on employers who violate the law is crucial, she said, and it isn’t right to employ people who are here illegally. But without a visa system allowing unmet labor needs to be addressed with foreigners, she said, ICE shouldn’t expect patchwork enforcement stings to persuade farms, hotels or meatpackers to stop employing unauthorized workers.
“When your laws don’t align with the market, then the market is always going to win,” Ms. Meissner said.
Advocates for immigrant workers said the raids were just the most recent source of a quiet terror reverberating across factory floors since Mr. Trump took office.
“When you have such a public thing happening close to home, folks feel the presence of ICE constantly,” said Mariela Martinez, the organizing director of the Garment Worker Center in Los Angeles. But her clients have families and children here, Ms. Martinez said, so they can’t just pack their bags and go.
“It’s not motivating people to self-deport,” she said. “It’s motivating people to not use their labor rights. It’s causing people to distrust government agencies.”
Ms. Martinez helps people in the garment industry file claims for back pay with the state when their employers pay them less than they’re owed. She said far fewer workers asked for restitution last year compared with 2016, partly because of concern that their bosses would call ICE if they spoke up.
That was the punishment one manufacturer meted out to Pablo, a 36-year-old sewing worker in Los Angeles who would not give his last name because he lacks papers and fears being identified by ICE. When he received a check for $92 after working three 11-hour days at a garment factory last month, Pablo insisted that he deserved more.
His boss responded by offering to pay him what he was owed, but only if Pablo offered up his home address. After signing another check, Pablo said, the factory owner said that he would call immigration officials and direct them to Pablo’s door.
“You feel terrible. You feel uncomfortable,” Pablo said. “I was so scared.” He called Ms. Martinez and they returned together the next day to tell the employer that the threat constituted illegal retaliation under California law. The employer backed down.
The 7-Eleven raids will give garment bosses even more control over their workers, Pablo said.
“Now they know the president is on their side,” he said, “so they feel like they can intimidate people and treat them badly and they will never talk.”
Still, Pablo has been here since he was 17, and has no plans to leave yet. He has bills to pay.