CIUDAD JUÁREZ, Mexico — A crackdown on illegal immigration has sharply curbed the number of Central Americans and others trying to enter the United States. But Mexicans, who have not been bound by some of the same restrictions, have been showing up at the border in greater numbers, in many cases fleeing the escalating violence in their country.
Thousands have been stuck for weeks here in Ciudad Juárez and other border cities, waiting for permission to cross into the United States to apply for asylum. Human rights advocates say the bottleneck violates American and international law by forcing migrants to remain in a country where they feel their lives are at risk.
“We’re fearful here because you never know whether at any moment someone’s going to come and kill someone,” said Juan, 55, a farm laborer from the state of Zacatecas who fled with 10 members of his family after his son escaped a criminal group that was pressuring him to join their ranks.
“Wherever we are in Mexico, the gangs can find us,” said Juan, who, like many asylum seekers interviewed for this story, asked to be identified by his first name only out of fear for his safety.
The Trump administration has also pressured the Mexican government to get tougher on illegal migration, leading to the deployment of thousands of Mexican security forces to help detain undocumented migrants as they travel north.
Those strategies have led to a sharp drop in the number of migrants trying to cross into the United States, officials say.
But the policies have had little impact on Mexican migration because Mexicans cannot be prevented from traveling through their own country to the northern border. And Mexican asylum seekers who have entered the United States, once they apply for protection, cannot be returned home unless their petitions are denied.
While the overall number of migrants arrested along the southwest border has plunged, the number of Mexicans apprehended has risen: About 17,000 Mexicans were caught crossing between ports of entry in October, a 34 percent increase since July, according to the United States Customs and Border Protection.
The number of Mexicans seeking American asylum has also shot up in recent months, advocates and Mexican officials say.
As the numbers have increased, American border guards have mostly turned away the asylum seekers at the official border entrances, saying they have no capacity to receive new applicants, migrants and their advocates say.
The practice has forced thousands of Mexicans to wait along the border for a chance to make their case in the United States. Here in Ciudad Juárez, they have been sleeping under plastic tarps in squalid encampments near the three main border bridges, enduring falling temperatures and bitterly cold rains.
The Mexicans have joined many thousands of asylum seekers from other countries who have also been compelled to wait in Mexico after the United States began to severely restrict the number of cases it takes in a day, a system known as “metering.”
Migrants’ advocates say the bureaucratic backup is particularly dangerous for Mexicans, who are being forced to wait in the country they are trying to flee.
The Trump administration “is focused on bringing immigration basically down to nothing and in doing so they’re again destroying a system set up by Congress to protect the most vulnerable arriving at our borders,” said Shaw Drake, policy counsel for the American Civil Liberties Union Border Rights Center in El Paso.
The A.C.L.U. filed a complaint last month with the Office of the Inspector General at the Department of Homeland Security calling for an investigation into the metering practice, with a special focus on the policy’s impact on Mexican migrants.
In recent weeks, the Trump administration has quietly launched a pilot program in El Paso designed to expedite the adjudications of Mexican migrants seeking asylum — and speed the return of rejected applicants. The initiative comes as Homeland Security officials say they have been frustrated by the recent surge of Mexican migrants crossing the border.
The Department of Homeland Security did not answer questions regarding the backup of Mexican asylum seekers along the border.
On a recent morning, more than 1,500 Mexican asylum seekers were waiting in Ciudad Juárez. Some had been stuck there for as long as two months. Nearly all were from the states of Michoacán, Zacatecas or Guerrero — regions where organized crime groups flourish.
A chilly wind was whistling through the encampment at the foot of the Córdova-Las Américas International Bridge, where Juan, the farm laborer, had settled with his family in September. Their shelter was a tent of plastic tarps where they bathed with water stored in five-gallon paint buckets, ate food distributed by charities and slept under donated blankets.
The whole family was sick with colds, he said.
“For those of us who haven’t made it across, we have to shiver for a bit,” he said. “I hope the United States government softens its heart so that more people can cross before the freeze comes.”
Juan’s son Manuel, 24, said the family had continued to receive threats from the criminal gang that kidnapped him. Manuel’s sister pulled out her phone and displayed a series of menacing messages. One read, in part: “Hand over your brother to us because we already know where you are.”
“These things aren’t easy,” Juan said.
Waiting lists managed by the migrants themselves and handwritten in well-worn notebooks govern the order in which families cross. On some days a few are allowed in. On others, none.
The wait in the makeshift encampments has been grueling, but many migrants say they chose it over staying in one of the city’s migrant shelters because they feared that if they were not present, they would lose their place in line and miss their opportunity to cross.
“When you leave your home, you leave with energy to deal with whatever you have to, because it’s better than what you have to deal with there,” said Martín, 37, a firefighter who fled his home in the state of Michoacan with his wife and three children because of violent persecution. He declined to provide further details to protect his identity and avoid jeopardizing his case.
Officials from the state of Chihuahua, where Ciudad Juárez is, say they have nothing to do with the Mexican lists because they do not want to be associated with something that might be against asylum law.
American officials have attributed the timing of the surge in numbers of Mexicans trying to cross the border to a change in strategy by migrant smugglers who have seen their businesses collapse as migration from Central America has diminished.
“They go to Mexico and they start taking out social media ads and going to Mexican nationals and telling them, ‘If you grab a kid, that’s your passport to the United States,’” Mark Morgan, the acting commissioner of Customs and Border Protection, said in October.
But some two dozen migrants interviewed in the Ciudad Juárez encampments said their decision had nothing to do with a smuggler’s marketing appeal. All said they were fleeing violence.
Some said that there had been a shift in the nature of violence in their home regions. Others said that while they had suffered violent persecution for months if not years, they only just learned about asylum and their possible eligibility.
“Before, if you were pursued by the criminals, you just suffered it and suffered it until they killed you,” said Jacobo, 42, an agricultural laborer who fled his home in Zacatecas with his wife and two children. “But now we know about political exile.”
Still others were motivated by rumors that the American authorities were allowing more Mexicans into the United States even while they were restricting access to Central Americans and others.
Regardless of the timing, advocates say, the sheer numbers — and a failure in American border policy — have generated a crisis that deserves immediate attention.
“These systems for considering and processing refugee claims exist for a reason,” said Mr. Drake of the A.C.L.U. The Trump administration “is not following the process that Congress requires them to and is thereby exposing thousands of people to potential harms that they should never have been exposed to.”
Zolan Kanno-Youngs contributed reporting from Washington, and Caitlin Dickerson from New York.