For 11 hours on Wednesday, drivers who wanted to travel through a remote stretch of northern Maine were asked a simple question: Where were you born?

Border Patrol agents closed off all southbound lanes of Interstate 95 north of Bangor, Me., stopping drivers, searching outside their cars with drug-sniffing dogs and refusing to let them pass until they disclosed their citizenship. At least one encounter was captured on cellphone video.

“Good afternoon, ma’am, U.S. Border Patrol immigration inspection,” an officer told two reporters with the Bangor Daily News who had heard about the checkpoint, about 80 miles from the Canadian border and decided to drive to it and record their interaction. “What country are you a citizen of?”


The driver protested. “If you want to continue down the road, then yes, ma’am, we need to know what country you’re a citizen of,” the agent said.

Such immigration checkpoints on highways have been used by the Border Patrol for years, often along popular smuggling and drug-trafficking routes in the Southwest. But their frequency has increased under President Trump, federal officials have said. The one in Maine was set up several days after agents conducted a three-day checkpoint on a New Hampshire highway, at least the second checkpoint in that state so far this year.

The recent checkpoints in Maine and New Hampshire resulted in the seizure of drugs and the arrest of at least six people on charges of being in the country illegally, according to Customs and Border Protection. Federal officials say the checkpoints are vital to confiscating illegal weapons, capturing suspected terrorists and catching people believed to be in the country illegally.

But drivers who encounter the checkpoints have long complained about them, saying they create unnecessary traffic jams and largely inconvenience local residents. They have also drawn the attention of legal groups, including the American Civil Liberties Union, who have questioned the constitutionality of the checkpoints and sued the federal government twice in the past year over immigration stops in New Hampshire and Maine.


However, Border Patrol agents have been given broad legal authority, which has expanded during the current administration, to conduct the stops and other operations, and to ask anyone about their immigration status.

Inspections have also extended to bus and train stops, where federal agents in Florida, Maine, New York and Washington State have recently asked riders about their immigration status.

While the agency’s name might suggest that its purview is limited to the immediate border, officers can work in any area within 100 miles of the perimeter of the United States. It is a wide swath of the country that is home to an estimated 200 million Americans and fully covers at least 11 states. Maine’s international borders with Canada and the Atlantic Ocean make the entire state open to immigration authorities.

It is difficult to determine how often the Border Patrol conducts highway checkpoints or stops riders at transportation stations. Customs and Border Protection issues news releases about the results of some of the stops but does not publish comprehensive details on how often they occur or how many people are stopped.

The nearly six-minute video of the Maine encounter offered a window into the reach and power of the Border Patrol at a time when its enforcement of the Trump administration’s “zero-tolerance” policy has come under intense criticism. The reporters asked a Border Patrol agent why the checkpoint had been set up.

“It’s just a random checkpoint. It’s within 100 miles of the border,” the agent said. “We just occasionally set them up to see what we can catch.”


The agent added that the officers look for signs that include how people answer their questions and if they speak with an accent. He argued the stops were fair and free of potential bias because every person who passed through the checkpoint was asked the same question.

Border Patrol officers have long come under criticism for why they decide to stop some people and not others. They have been accused of making subjective and arbitrary judgments. Customs and Border Protection instruct agents not to consider a person’s race or ethnicity.

Agents are also barred from considering a person’s language, an issue that surfaced in an encounter in Montana last month. A Border Patrol agent overheard a woman speaking Spanish to a friend inside a convenience store in Havre, a small town about 30 miles south of Canada. He stopped the women and asked for their proof of citizenship, later telling them that their Spanish had raised suspicions. The friends were United States citizens.

Emma E. Bond, a staff attorney at the American Civil Liberties Union of Maine, said she found it troubling that the Border Patrol agent in the Maine video mentioned that officers take note of a person’s accent.

“The Fourth Amendment requires explicit, neutral limitations on the conduct of individual officers,” Ms. Bond said Friday. “Yet here, the Border Patrol officer in the video claimed that ‘it’s the agent’s determination’ whether to detain people and that suspicion could be based on ‘accent, could be anything.’”

The Maine checkpoint, which led to one person being arrested on immigration-related charges, was set up following a similar checkpoint last Friday through Sunday on Interstate 93 in Woodstock, N.H., about 90 miles from the Canadian border. Federal agents there arrested five people suspected of being in the country illegally and seized “various narcotics and drug paraphernalia,” the agency said.

“Operations of this type are within the jurisdiction of the Border Patrol and performed in direct support of immediate border enforcement efforts,” said Steve Sapp, a spokesman at Customs and Border Protection, “and as a means of preventing smuggling organizations from exploiting existing transportation systems to travel to the interior of the United States.”

The A.C.L.U.’s offices in New Hampshire and Maine have challenged the Border Patrol’s immigration checks on highways and at bus stops. The group filed a lawsuit in New Hampshire last year after a checkpoint in Woodstock resulted in the arrest of several people on drug charges. Last month, a judge agreed and ruled in favor of the A.C.L.U., saying that the stops violated both state and federal constitutions.

Ms. Bond said her group sued last month to obtain details on checkpoints and immigration inspections in Maine, after the federal government declined to provide them.

“We know there is a nationwide crackdown on immigrants and increased C.B.P. presence at bus stops,” Ms. Bond said. “Coupled with highway checkpoints, it’s hard not to feel that we are living in a ‘show-me-your-papers’ state.”