Tornillo, Texas • Workers compared it to a giant slumber party.

Flowers made of plastic bottles, chains of colorful construction paper and pictures of Disney princesses stripped from coloring books adorned dozens of bunk beds inside a cavernous white tent where hundreds of Central American teenagers have spent the past several weeks.

On the other side of what looked like a military base, in smaller beige tents that housed up to 20 young men apiece, faux spider webs were strung across the bed frames for Halloween. Clusters of Spanish-speaking teens placed strips of blue tape across their chests to indicate their team affiliation as a spirited soccer match took place on a makeshift pitch of dirt and synthetic grass.

The 123-tent complex 30 miles from El Paso is a holding facility for undocumented youths who crossed the U.S.-Mexico border and are waiting to be reunited with parents and relatives. About 1,500 minors are housed there.

Officials at the U.S. Department of Health and Human Services, which contracts with a nonprofit organization to run the facility, took reporters on a tour Friday, providing a glimpse at one facet of the nation's evolving migrant crisis.

The temporary overflow center opened in June, when a network of about 100 HHS-contracted shelters across the country was approaching capacity because of a steady flow of minors across the border and a growing wait for relatives and other potential sponsors to get through background checks.

At the time, the estimated 12,000 minors in HHS custody included more than 2,500 children separated from their parents or other adults at the border as a result of President Donald Trump's crackdown. Most of those separated children have since been reunited with parents or released to a sponsor, according to the latest filings in a lawsuit challenging the separations.

But the amount of time it takes to vet potential sponsors for unaccompanied minors continues to grow. As a result, the government has more than tripled the number of beds at Tornillo to potentially accommodate up to 3,800 young migrants.

About 3,200 minors have passed through Tornillo so far, staying 29 days on average. The highest number of occupants at any one time was 1,630 adolescents ages 13 to 17, most of them boys, officials said. All had previously spent time in other shelters and were close to being released.

"This is their last stop," HHS spokesman Mark Weber said.

The department estimates that nearly 51,000 children will cross the border this year unaccompanied — the third-highest one-year total in history, officials said. As of August, they spent an average of 59 days in HHS custody.

BCFS, the San Antonio-based nonprofit organization that operates Tornillo, specializes in erecting emergency housing after natural disasters. Some of the tents at Tornillo were used to shelter people displaced by last year's Hurricane Harvey. HHS said in a notice in the Federal Register last month that it will pay up to $367.9 million between mid-September and December to operate the shelter.

Department officials said they want to release children to sponsors as quickly and as safely as possible, but they are also wary of past mistakes in which minors were mistakenly handed off to human traffickers.

BCFS does not allow migrant children to keep cellphones at the camp because of fears they will be contacted by traffickers who helped bring some of them into the country. The youths can call relatives who are on an approved list on phones provided by the federal government. They have no access to the Internet.

Camp residents wear lanyards around their neck that hold photo ID cards listing their date of birth and date of arrival at Tornillo.

As part of its screening efforts, the Trump administration is asking potential sponsors and members of their households to provide fingerprints and undergo background screening before children can be released to them.

A new information-sharing agreement between HHS and the Department of Homeland Security has increased concerns that some potential sponsors, many of whom are in the country illegally, will be scared to come forward, knowing their information could be accessible to immigration enforcement agents.

But officials said that risk has not stopped thousands of parents and other relatives from applying as sponsors.

The tent facility’s incident commander, who spoke to reporters on the condition that his name be withheld, said more than half of the youngsters at the tent camp — 826 — can be released as soon as FBI background checks are completed.

When asked why there were still in Tornillo, several children said, “Huellas!” — Spanish for “fingerprints.”

Advocates say they are worried about the level of oversight at Tornillo, even more than at other shelters, because of the large number of children and teens housed there and the relatively austere nature of the facility.

"Anyone who keeps children has to be licensed by the state of Texas, except the federal government," said Patricia Macias, a retired Texas family court judge. "Who is keeping the government accountable?"

But the incident commander said his program exceeds Texas's child-care standards regulating such things as the adult-to-child ratio (8 to 1), safety features (24-hour fire and EMS service) and access to lawyers and mental-health and social workers. Not one child has tried to escape or has been seriously ill, he said.

BCFS started offering classes in basic social studies, math, science and English in recent weeks, supplying the young migrants with workbooks and hiring retired teachers to help lead sessions.

"They are receiving education, but this is not school," he said.