Border Apprehensions Reach Highest Level in at Least 15 Years

The Biden administration apprehended more than 170,000 migrants at the southwest border in March, the most in any month for at least 15 years and up nearly 70 percent from February, as thousands of children remained backed up in detention facilities and border agents released an increasing number of migrant families into the United States, government documents obtained by The New York Times show.

The sharp increases underscored the political and logistical challenges to the administration of managing the flow of people coming from Central America, including the need to more quickly move unaccompanied children and teenagers into emergency shelters at military sites and conventions centers throughout the United States. Many of the children are seeking to join parents, relatives or other people they know who are already in the country.

But the increasing number of family members traveling together is creating another issue for the administration. For much of the winter, even as the United States took in the unaccompanied minors, administration officials invoked an emergency rule put in place by the Trump administration during the pandemic to turn away most migrant families and single adults crossing the border.

The situation is rapidly becoming more complicated. For one thing, the sheer volume of families arriving is growing fast, with border officials encountering more than 53,000 migrants traveling as families in March, more than double the roughly 19,250 in the prior month.

American officials are also coping with a change in the law in Mexico, which has tightened its conditions for accepting Central American families expelled by the United States. Because of the new law in Mexico and a lack of space in shelters there for children, the United States can no longer send most families with a child under the age of 7 back across the border.

At the same time, the United States does not currently have the capacity to detain large numbers of families, leaving border officials with few options other than to release them with orders to appear in the future to have their cases heard.

“We’re entering phase two of this extraordinary migration event,” said Cris Ramón, an immigration consultant based in Washington. “At this point, the scope of the individuals who are coming means the administration is going to have to now address the challenges of not only building capacity for unaccompanied children, but they’re going to have to expand this capacity for families.”

The overcrowding in facilities has prompted border agents to release more families into communities along the border, according to officials. Some of those who have been released were not fully informed about the details of their upcoming court appearances, those officials said.

Authorities have dropped off families with children at bus stations in border communities, where they then continue their journeys north to relatives in the United States. Border officials encountered more than 1,360 migrants traveling as part of families on Sunday and expelled just 219, according to the documents. On March 26, more than 2,100 families were detained and just 200 were turned back south.

“We are seeing the numbers increase day by day. They increased tremendously, especially in March,” said Hugo Zurita, the executive director of Good Neighbor Settlement House in Brownsville, Texas, which has been providing hot meals and items, such as clothing, hand sanitizer and masks, to migrant families at the city’s bus station.

Republican members of Congress, vowing to make the issue central to their efforts to retake control of Congress, have repeatedly accused the administration of encouraging the surge in migration with President Biden’s pledge to have more compassionate policies toward migrants than those imposed under President Donald J. Trump.

“They’re certainly going to be using this as a weapon against us,” said Representative Henry Cuellar, Democrat of Texas. “It’s taking away from Biden’s good work. He’s done a hell of a job on vaccines. It’s taken us away from the messaging we’ve had.”

The Biden administration has continued to use a pandemic-emergency rule to rapidly expel single adults, who continued to make up the majority of those caught at the border in March. Advocates for immigrants have criticized the rule as breaking with immigration laws that say migrants are entitled to apply for asylum upon reaching U.S. soil.

The White House has talked to at least one member of Congress about the possibility of expelling 16 and 17-year-olds to Mexico, according to a person familiar with the discussions.

The administration has also framed its response as focused on tackling the root causes of migration, appointing Vice President Kamala Harris to work with leaders in the region to bolster the economy in Central America and restarting an Obama-era program that allows some children to apply in their home region for permission to live in the United States with a parent or other relative.

“We are not naïve about the challenge but what our focus is on is solutions and actions to help address the unaccompanied minors who are coming across the border and making it less of an incentive to come,” Jen Psaki, the White House press secretary, said on Friday.

The crossings by unaccompanied minors present the more severe logistical challenge for Mr. Biden. Unlike single adults or migrants traveling as a family, the administration by law is responsible for the care of unaccompanied children and teenagers until it can match them with a sponsor in the United States.

Nearly 5,000 children and teenagers were in detention centers that were originally set up to hold adults on Thursday, including more than 3,300 held longer than the maximum 72 hours allowed under federal law, according to government documents. Within 72 hours, they are supposed to be transferred to the shelter system run by the Department of Health and Human Services.

More than 13,300 minors were held in the shelter system on Friday, according to the department. The administration is projecting it will need more than 35,000 beds for minors in border facilities and emergency shelters by the end of May, according to documents.

Alejandro Mayorkas, the homeland security secretary, said last month that the administration was expecting this year to encounter the most migrants at the border in 20 years.

“There’s no break on this,” said Ronald D. Vitiello, a former acting director of Immigration and Customs Enforcement and chief of the Border Patrol under the Trump administration. “It just gets a lot worse. It’s really unfortunate.”

Mr. Biden has now deployed the Federal Emergency Management Agency to find additional shelter space for the minors in an effort called “Operation Apollo.” The administration is still assessing housing migrants at new facilities at a hotel in Dallas, Fort Benning in Georgia and the Sleep Train Arena in Sacramento, according to government documents

“They should’ve been planning for this a month ago,” Mr. Ramón said. “Now they have to be thinking two or three months ahead to have a solution to deal with this.”