Federal immigration agents descended on dozens of 7-Eleven convenience stores across the country before daybreak on Wednesday, arresting undocumented workers and demanding paperwork from managers, in what the Trump administration described as its largest enforcement operation against employers so far.
The sweeps of 98 stores in 17 states, from California to Florida, resulted in 21 arrests, according to United States Immigration and Customs Enforcement, which signaled intensified efforts against businesses that hire unauthorized workers.
“Today’s actions send a strong message to U.S. businesses that hire and employ an illegal work force: ICE will enforce the law, and if you are found to be breaking the law, you will be held accountable,” Thomas D. Homan, the acting director of the agency, said in a statement.
Mr. Homan, the nation’s top immigration-enforcement official, has promised more scrutiny of businesses that knowingly violate federal laws requiring employers to verify the identity and employment eligibility of their workers.
Under President Trump, ICE has significantly expanded immigration enforcement, arresting undocumented immigrants in their homes or when they check in with federal agents as part of immigration court cases.
In a statement, 7-Eleven Inc., based in Irving, Tex., distanced itself from the situation, saying that the individual stores are franchises that belong to independent business owners, who “are solely responsible for their employees, including deciding who to hire and verifying their eligibility to work in the United States.”
“7-Eleven takes compliance with immigration laws seriously and has terminated the franchise agreements of franchisees convicted of violating these laws,” the company said.
If ICE hoped to make a bold statement, it could hardly pick a more iconic target than 7-Eleven, a chain known for ubiquitous stores that are open all the time and sell the much-loved Slurpees and Big Gulps. Many a 7-Eleven franchise has been a steppingstone for new legal immigrants who want to own and run their own small businesses.
Not all franchisees have been scrupulous about whom they hire. ICE called its Wednesday sweep a “follow-up” of a 2013 investigation that resulted in the arrests of nine 7-Eleven franchise owners and managers on Long Island and in Virginia on charges of employing undocumented workers. Several have pleaded guilty and forfeited their franchises, and have been ordered to pay millions of dollars in back wages owed to the workers.
“This definitely sends a message to employers,” said Ira Mehlman, the spokesman for the Federation for American Immigration Reform, which favors more limits on immigration and stricter enforcement.
According to ICE, federal agents served inspection notices to 7-Eleven franchises in California, Colorado, Delaware, Florida, Illinois, Indiana, Maryland, Michigan, Missouri, Nevada, New Jersey, New York, North Carolina, Oregon, Pennsylvania, Texas, Washington State and Washington, D.C.
Employees at two 7-Eleven stores on Staten Island said that immigration agents visited the stores on Wednesday. But the agents were shown valid employment records with Social Security numbers, two workers at each of the stores said, and no one was arrested.
In all, 16 of the 98 stores visited on Wednesday were in the New York City area, according to an ICE spokeswoman, Rachael Yong Yow, who would not specify their locations.
In Miami Beach, an employee at one 7-Eleven said that while no agents showed up at her store, her boss asked workers to make sure their employment records were up to date, in case ICE continued its visits. Agents dropped in on 7-Eleven stores in seven cities in southeast Florida, including Miami Beach, according to Nestor Yglesias, an ICE spokesman; he, too, declined to identify specific stores.
Under President George W. Bush, ICE grabbed headlines by rounding up unauthorized workers at meatpacking plants, fruit suppliers, carwashes and residences. In a shift, the agency under President Barack Obama focused on catching border crossers, deporting convicted criminals and pursuing employers on paper, by inspecting the I-9 forms that employers are required to fill out and keep to verify their workers’ eligibility.
By targeting 7-Eleven franchisees and their workers on Wednesday, ICE under Mr. Trump appeared to be melding the approaches of his two predecessors: Go after employers while also detaining employees whom agents encountered without work authorization.
One of the biggest workplace immigration raids, in May 2008, resulted in the detention of nearly 400 undocumented immigrants, including several children, at an Iowa meatpacking plant. Sholom Rubashkin, the chief executive of the Agriprocessors plant, which was then the largest kosher meatpacking operation in the country, was eventually convicted of bank fraud in federal court.
President Trump commuted Mr. Rubashkin’s 27-year prison sentence last month, after years of lobbying by a number of prominent lawyers and politicians who considered his term unduly harsh, and perhaps even anti-Semitic.
An earlier version of this article misstated when nearly 400 people were detained in an immigration raid at an Iowa meatpacking plant. The raid was in May 2008, not July.