Central America

Terrifying, heart-rending, defeating: 10 hours on patrol along the Mexican border

A dispatcher's voice crackled over the scanner, and Raquel Medina turned up the sound. Traffic north of the river. An agent had spotted footprints in the dirt.

Medina gunned the engine of her green and white U.S. Border Patrol truck, drove down a dirt road, pulled over and plunged into the mesquite brush. It was 106 degrees.

She darted through spiny bushes that reached above her 5-foot-8-inch frame. A branch caught her frizzy brown hair, coiled in a bun. Those could be families up ahead, in which case there would be no need for the handcuffs dangling from her right hip. Or children traveling alone. They could be men smuggling drugs or inked with teardrop tattoos, meaning...