Nearly 1,500 boys are crammed into overcrowded rooms and reportedly given only two hours fresh air a day at Brownsville’s Casa Padre, the largest centre of its kind in the US.
Many were forcibly separated from their families under the Trump administration’s “zero-tolerance” policy after illegally entering the country, according to MSNBC correspondent Jacob Soboroff.
The number of unaccompanied migrant minors held across 100 centres has swelled to more than 11,000 in the weeks since the government launched the aggressive campaign to deter families crossing the border.
A 20-per-cent rise in children being held has brought the facilities to the brink of capacity, with the Department of Health and Human Services (HHS) now looking at building tent cities at military bases to hold thousands more minors.
Mr Soboroff, one of the first reporters allowed to tour Casa Padre after the zero-tolerance policy was introduced, said most children slept five to a room in dormitories designed only for four.
The government has allowed the centre, a converted supermarket run by private firm Southwest Key, to exceed that limit because of overcrowding.
“Kids here get only two hours a day to be outside in fresh air,” Mr Soboroff said. “One hour of structured time. One hour of free time. The rest of the day is spent inside a former Walmart.”
He added: “I have been inside a federal prison and county jails. This place is called a shelter but these kids are incarcerated.
“No cells and no cages, and they get to go to classes about American history and watch [Disney film] Moana, but they’re in custody.”
Children entering the facility for the first time are greeted by a mural of Donald Trump. Alongside images of the president, the American flag, and the White House, are words he once tweeted: “Sometimes losing a battle you find a new way to win the war”.
“[There are] presidential murals everywhere,” Mr Soboroff. “But that one is first.”
There is also a mural of Barack Obama.
“My fellow Americans, we are and always will be a nation of immigrants. We were strangers once, too,” reads his quote, in English and Spanish, taken from a 2014 speech in which he announced protections for undocumented immigrants.
Lights at the shelter go off at 9pm and come on again at 6am.
Children eat and attend school in shifts. They are taught in numbered classrooms with tiny windows, through which they waved at reporters during the tour, also attended by the Washington Postand local media.
“You might want to smile,” journalists were told by a Southwest Key employee. “The kids feel a little like animals in a cage, being looked at.”
The centre’s detainees, all boys aged 10 to 17, stay an average of 52 days before they are placed in foster care or with other relatives.
“The lack of parental protection, and the hazardous journey they take, make unaccompanied alien children vulnerable to human trafficking, exploitation and abuse,” a spokesman for the Administration for Children and Families at the HSS told The Independent.
“In some cases many violent gangs, including MS-13, are exploiting loopholes in US laws to bring gang members into the United States or recruit unaccompanied alien children once placed with a sponsor,” he added.
The spectre of gangs has been used by Mr Trump's administration as part of its justification for the crackdown on undocumented migrants and the detention of their children.
However, staff at Casa Padre told MSNBC they had “never had an MS-13 member here, ever”.
The journalists’ visit to the shelter came days after a US senator was turned away and spoken to by police after trying to gain access.
The HSS refused to arrange a tour for Jeff Markley, who said it was “unacceptable that a member of Congress is not being admitted to see what is happening to children whose families are applying for asylum”.
Texas regulators have found hundreds of health violations, including a lack of supervision and medical care, at shelters for migrant children run by Southwest Key.
The policy of separating detained immigrant parents from their children has been driven by attorney general Jeff Sessions, who hopes it will dissuade families from crossing the border.
“If people don’t want to be separated from their children, they should not bring them with them,” he said in an interview with conservative radio host Hugh Hewitt last week.
Related Video: Inside a Texas Child Detention Facility