A punctured raft hangs in the water as migrants, including children, climb the banks of the Rio Grande in Penitas, Tex., on March 6 after being smuggled into the United States. (Adrees Latif/Reuters)

They cross the border from Mexico in groups large and small, most of them teenagers, but some much younger, carrying the names and phone numbers of family members living in the United States. Home is hundreds, if not thousands, of miles away. Some make the journey with a smuggler or a friend, but others set out alone, traveling on buses, the tops of freight trains or even by foot.

Central American and Mexican children, tweens and teenagers traveling without parents are crossing the border in soaring numbers, once more creating a logistical and humanitarian emergency for the U.S. government.

Some are fleeing violence, poverty and gang recruitment in their hometowns, risking the dangerous trip north in hope of finding safety or maybe a job that will pay exponentially more than they could make at home. The U.S. government labels them “unaccompanied minors,” and the Biden administration is struggling to shelter and care for them.

The U.S. refugee office of the Department of Health and Human Services has more than 8,500 minors in its shelters this week. An additional 3,500 are stuck in Border Patrol stations waiting for beds to open up. Each day, an additional 500 or more arrive, a threefold increase since December, and nearly 700 arrived Wednesday, the latest figures show. If the climbing trend line continues, the Biden administration will take in record numbers of unaccompanied minors this month, an influx made more challenging by the coronavirus pandemic.

By law, U.S. Customs and Border Protection must transfer the minors to HHS facilities within 72 hours, but the latest government data show they are spending 107 hours on average in bare-bones detention cells built for adults. To accommodate the growing numbers and meet social distancing guidelines, the administration opened a tent facility in Carrizo Springs, Tex., last month. The Biden administration is planning to open additional tent sites in the coming weeks and is looking at Moffett Field in California, Fort Lee in Virginia and other federal properties where it can set up temporary shelters.

The surge is similar to others that occurred in 2014, 2016 and 2019, but also potentially larger, because conditions in Central America and Mexico are more desperate as a result of the pandemic’s economic pain.

Teenage boys make up the largest group. HHS statistics show that 70 percent of unaccompanied minors are male, and that about 75 percent are ages 15 to 17. Teenagers making the journey are particularly vulnerable to exploitation, abuse and forced recruitment by gangs, smugglers and predators. Sexual assault is common. Among about 400 adult respondents to a Doctors Without Borders survey in 2017, 31 percent of women and 17 percent of men said they were sexually assaulted along the trip.

Most unaccompanied minors cross the border into the Rio Grande Valley of South Texas. Some try to evade capture after crossing, but most seek out U.S. border agents to begin the process of making a humanitarian claim.

A young man is apprehended by U.S. Customs and Border Protection officials at the U.S.-Mexico border near Mission, Tex., on Feb. 10. Nearly 100 migrants were apprehended in about an hour. (Sergio Flores for The Washington Post)

There are also indications in recent weeks that some minors are traveling with a parent to the border and then splitting up. The Mexican government last month stopped taking back some families “expelled” by U.S. authorities under an emergency public health order, forcing CBP to release them into the United States. There are anecdotal reports that some parents with older children or teenagers are sending the minors across alone, then attempting to sneak across the border separately with the goal of reuniting later.

The difficult and anguished decision to send a child or teenager alone is not an irrational act. The odds of being deported are low. DHS statistics show that just 4.3 percent of the 290,000 minors who have crossed the border without a parent since 2014 have been returned to their countries. Of the rest, 52 percent had immigration cases pending. An additional 28 percent had been granted humanitarian protection by U.S. courts and 16 percent had been ordered to leave, but lacked a confirmed departure or deportation.

The vast majority of the unaccompanied minors are from Mexico and Central America, but trends have shifted in recent years. In 2014, during the first major crisis, the number of minors crossing from El Salvador, Guatemala, Honduras and Mexico was about even. During the 2019 surge, Guatemalans and Hondurans were by far the two largest national groups. Last year, unaccompanied minors from Mexico comprised about half of all those taken into CBP custody.

HHS oversees an extensive network of shelters for the minors. Some are specialized, providing care to youths with trauma, medical needs or behavioral problems. Another subset cares for teenage mothers who arrive with infants and young children.

It’s a system of bricks-and-mortar facilities that often struggle to cope with sudden changes in the volume of minors. More than 13,000 beds are available in the HHS network, but capacity was limited by pandemic distancing guidelines. Last week, the government eased those limits to return to full capacity, despite the health risk. HHS officials have told the White House that they need about 20,000 shelter beds to keep pace with the influx.

Sunlight shines through window coverings inside a bedroom at an influx care facility for unaccompanied immigrant children on Feb. 21 in Carrizo Springs, Tex. The facility has dormlike rooms with areas for eating, bathing, and even haircuts and laundry. (Sergio Flores for The Washington Post)

The Biden administration’s rush to open “soft-sided” tent facilities as emergency shelters has angered some Democrats on Biden’s left flank. They liken the tent sites to jails or the chain-link enclosures inside a Border Patrol warehouse that were widely denounced as “cages” in 2018 when the Trump administration separated thousands of children from their parents in an attempt to deter family migration.

But the HHS shelters bear little resemblance to those detention cells. They are by no means the kind of “summer camp” environment some defenders claim, but they resemble a makeshift group home, with classrooms, games, movies and outdoor recreation spaces. Private child-care contractors and counselors — not armed federal agents — interact with the minors.

Once a minor is in HHS custody, the agency must identify a sponsor eligible to take custody and vet that person. About 90 percent of the minors are released to relatives living in the United States, and in about half those instances, the relative is at least one of their parents. Often, these relatives are living in the United States illegally, and a lack of records can complicate the process.

Sponsor data collected by HHS shows the leading destinations are the Dallas, Houston and Los Angeles metro areas, which have large Central American communities. Florida and New York are also among the leading destinations, but the Washington, D.C., metro area appears to receive more unaccompanied minors per capita than anywhere else in the country.

The latest statistics show the average length of time a minor spends in an HHS shelter is 30 to 40 days, and the government has been wary of speeding the process. In one 2014 incident, teenagers released by HHS ended up with traffickers who sent them to work at an Ohio egg farm. Lawmakers were furious, and HHS officials say their obligation is to err on the side of caution.

Biden officials have taken steps to place minors more quickly, offering to pay travel costs for minors whose parents cannot afford plane tickets. They are also working with advocacy groups to identify minors in northern Mexico who are preparing to cross, so that they can do so safely at a legal port of entry, instead of paying a smuggler to cross the Rio Grande.

“The Biden administration is rightly saying it’ll take time to reconstruct the system in a humane and appropriate way,” said Wendy Young, president of the advocacy group Kids in Need of Defense, which is helping with the effort. “And they’re digging themselves out of a hole right now.”

A Texas State Trooper asks asylum-seeking migrants Edith and her son Harbin Ordonez, 4, to come out of hiding after the Honduran nationals crossed the Rio Grande into the United States from Mexico on a raft in Penitas, Tex., on March 9. (Adrees Latif/Reuters)

The data and methodology behind this article have been made available on GitHub.