Ashley Esquivel’s alarm goes off at 5:45 a.m. in Juárez, Mexico. It’s a Friday in November, and she’s heading to high school in Texas, which means football. She pulls on blue sweats branded with the frowning bear mascot of her high school, stuffs her cheerleading skirt into her backpack, and gets in the car. Her dad drops her at the U.S. border on his way to work.

Although the days are still warm, dawn in the desert hovers around 30 degrees. A yellow mist settles across a motionless line of cars that seems to stretch from the horizon to the border checkpoint. Vendors hawk newspapers and burritos to commuters bound for El Paso, who can wait three or four hours to