Port Isabel Detention Center, Los Fresnos, Texas

Port Isabel Detention Center is at the end of a long road lined with bush and cotton fields in the Rio Grande Valley of southern Texas, ten miles from the Mexican border. Around 1,200 people detained by US Immigration and Customs Enforcement are held there at any given time. Some were apprehended at the border. Others were arrested after a traffic violation. In 2015 the US Civil Rights Commission found that the center violated the Fifth Amendment rights of migrants detained there because it did not offer due process protections, although the conditions resembled those of a jail. A few years ago, a former guard was sentenced for groping female detainees when they were alone in the infirmary. Reports of abusive behavior by guards are common, as is retaliation—last year, one woman was forced into solitary confinement and was “subject to starvation” for trying to tell a visiting official that she had been separated from her child. Still, one local immigration lawyer told me, it’s not as bad as other places a detained migrant might end up. At least there’s a library. At least there are medical services.

On Wednesday, August 7, buses sat in the parking lot ready to pick people up or drop them off; men walked through the courtyard of the facility in a straight line. A family in the waiting room sat by a machine called “GettingOut,” through which relatives can send money and photographs to inmates, for a fee. A cart highlighted Port Isabel Detention Center’s annual food drive, “Feds Feed Families.” A green and cheerful holiday resort, with a golf course and peaceful bicyclists, was only a short car ride away.

All three flags in the parking lot were at half mast. Four days earlier, a white man had brought a gun to a Walmart in El Paso and killed twenty-two people. In a document he posted online, which the media were calling a manifesto, he decried “the Hispanic invasion of Texas.” The Rio Grande Valley is over 90 percent Hispanic. Shoppers worried about copycats. A Walmart in Weslaco, about five miles north of the border, closed because of threats against it; a mother brought her thirteen-year-old into the police station the next day to confess. In Harlingen, a few miles east, police looked for a twenty-one-year-old who had threatened to shoot up the Walmart in that town. News reports talked of tense malls, despite the back-to-school tax breaks. Kids begged their parents not to buy groceries.

At Port Isabel, inmates in a small courtroom were struggling to understand how to…