The shelters in and near Brownsville have become big business, employing hundreds of residents and bringing abandoned stores, schools and other buildings back to life in a county where the median household income is $34,578 and the percentage of those living below the federal poverty line is 29.1, far higher than the national poverty rate of 12.7 percent.

But they have also raised questions about federal oversight and management, and the invisibility under which many of them operate.

Numerous shelters that care for unaccompanied migrant youth in Texas have been cited by state child care facility regulators for dozens of violations in recent years, according to data from two of the state’s oversight agencies, the Texas Health and Human Services Commission and the Department of Family and Protective Services. The majority of the violations were for minor infractions, including incomplete child records. But some were for more serious problems.

At least 13 deficiency citations have been filed against the shelter at the former Walmart in Brownsville, which seemingly overnight became a symbol of the housing scramble after a Democratic lawmaker, Senator Jeff Merkley of Oregon, showed up unannounced to take a tour but was turned away by police escort. Mr. Merkley’s attempt to gain entry this month, captured on Facebook Live by a member of his staff, put national attention on the shelter, which is run by a nonprofit group that contracts with a federal agency.

The shelters are part of the federal government’s attempt to accommodate a flood of young people who have been surging across the Southwest border over the past several years, often without an accompanying parent. Many of them are seeking asylum from gang violence or other troubles in Central America.

[A young mother in Guatemala is attempting to reunite with her 8-year-old son after they were separated during an attempt to cross the United States border. Read more here.]