BROWNSVILLE, Tex. — The mother in Room 211 was separated from her 17-year-old daughter by Border Patrol agents after they had crossed the Rio Grande on a tire. Since then, it had been 40 days. The same number as her age.

“It’s like each day is a year,” said the mother, who asked to be identified by her middle name, Isabella.

She sat in an Americas Best Value Inn one evening this week, eating beef fajitas. Dinner on a bed in a motel: Hers was a life in transit.

Isabella left El Salvador with her daughter to join her boyfriend, who has been living in the United States for more than a decade. The two crossed the river near the South Texas city of McAllen and turned themselves in. Isabella was put in one line at the Border Patrol facility and her daughter was put in another, and that was how they separated — suddenly, without warning or time for a long farewell embrace. Isabella was sent to a detention center in Laredo, Tex., and then to another nearly an hour outside Austin, called Hutto. She was released, and got a ride to Brownsville, where her daughter, identified by her middle name, Dayana, was being held at a children’s shelter.