Rep. Mark Pocan (D), left, joins other Democrats Rep. David N. Cicilline, Sen. Chris Van Hollen and Sen. Jeff Merkley in front of the Customs and Border Protection’s Rio Grande Valley Sector’s Centralized Processing Center in McAllen, Tex., on June 17. (Joel Martinez/The Monitor/AP)

As journalists and elected officials have gotten a chance to tour facilities in which children are being held after being separated from their families under the Trump administration’s “zero-tolerance” immigration policy, a question has cropped up on social media: Where are the girls?

The government has released photographs from inside the Casa Padre shelter in Brownsville, Tex., which some reporters have been able to tour. Others, including The Washington Post’s Sean Sullivan, toured a facility in McAllen, Tex.

Those government images depicted only boys, inspiring “where are the girls” and “where are the infants” questions on social media. (A similar question went viral in 2014 in an effort to draw attention to Nigerian girls kidnapped by the Islamist militant group Boko Haram.) Some people simply wanted an answer to the question. Others darkly suggested a conspiracy. Some made political points.

Homeland Security Secretary Kirstjen Nielsen was asked during a news briefing on Monday where the young girls separated from their parents are.

“I don’t know,” she replied.

But then she gave a reason for not knowing: Children separated from their parents are transferred into the existing system for children who arrive at the border alone, a process run by the Department of Health and Human Services, not the Department of Homeland Security. Nielsen referred questions to HHS.

Our repeated efforts to get specific answers from HHS were unsuccessful, but we know the answer to the question anyway.

Rep. Mark Pocan (D-Wis.) tweeted the answer after touring the facility in Brownsville, but he explained in more detail when we spoke by phone on Tuesday.

“There are separate facilities for younger children; there are separate facilities for girls,” Pocan says he was told. Because Brownsville and McAllen have been the focus of attention, only boys have been depicted. In a conference call with reporters on Tuesday, HHS officials pledged to release photos of detained girls and toddlers “within the next two days.”

In some cases, the same facility holds both boys and girls, though in separate areas. Our reporter noted in his article that “detainees had been sorted into groups — unaccompanied boys 17 and under; unaccompanied girls 17 and under; male heads of household with their families; and female heads of household with their families.”

The president of the organization Kids in Need of Defense, which provides legal services to unaccompanied minors, confirmed that separation in a statement to The Post. The Office of Refugee Resettlement, the HHS division that handles unaccompanied minors, “is opening a new facility in Houston for children under 12 and pregnant and nursing teens that can hold 230 people,” KIND President Wendy Young wrote, expressing concerns about the size of the facility.

In our conversation, Pocan made obvious that the question of where girls are being held is secondary to the questions that migrant parents have about their children in general.

“One woman pulled out a little piece of paper that said where her children were,” Pocan said of his visit to a detention facility for adults. “A piece of paper that she had in her pocket — that’s all she has to know where her children are. One woman told us that she was told by whoever she was talking to that her children are going to be put up for adoption. One person told us that they said they were going to release her eventually and then later they’d release her 9-year-old daughter, who’s being held in New York.”

Pocan reinforced that the separation from parents is geographic: Children also are being transported to other states.

That separation begins at a processing center where boys and girls are first separated from their parents and grouped by gender, held in “separate pods,” according to Young. Those 4 and younger remain with their parents at first.

Why? “At 5, you’re considered independent enough to go into a cage with people you don’t know,” Pocan said.

One important step, though, was missing.

“A mother mentioned, when they take away your children — sometimes they don’t tell the truth, they say it’s for a photo or something,” he said. “But they never ask about the children. Do they have an allergy? Have they ever been abused? Are there a certain kind of people they’re afraid of if they’ve had an abusive adult in their life? There’s no questions asked whatsoever, so it makes it very, very difficult to know if your child is safe.”

Those were the concerns of parents in the facility, Pocan noted, not that girls and toddlers had vanished to some unidentified location.

The concerns of the children, of course, were different.

“Imagine people who are afraid when they’re separated from their parents at the mall when you’re a child,” Pocan said, “much less to be put into a cage with people you don’t know and you don’t speak the language as the people around you who are essentially taking care of you.”

“It’s a very ugly situation,” he said.