LA JOYA, Texas (AP) — Marely had traveled for 13 days, trekking with her mother from Central America to the busiest corridor for illegal U.S.-Mexico border crossings. Then, as the 12-year-old Salvadoran girl got on an inflatable raft to cross the Rio Grande in Texas in the middle of the night, she discovered her mom wasn't coming with her.

Her mom told her that she loved her very much right before the boat got pushed into the water.

"I thought she had already gotten on, but she hadn't," Marely told The Associated Press this week, tears rolling down her cheeks.

But she didn't scream or ask the...