A Border Patrol agent shows reporter Diana Alba Soular what it takes to track signs of movement – and to stay alive – in the vast "Bootheel" of New Mexico, where agents spend hours a day driving and hiking mostly uninhabited borderlands alone, and crossers find increasingly clever ways to hide their tracks.

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This episode was recorded, edited and produced by Hannah Gaber, with field interviews and sound from Cheryl Evans and Pat Shannahan. Kaila White was our production manager. Our technical director was Nate Kelly. Special thanks to Ray Soular for recording help. It was written by Diana Alba Soular, Josh Susong and Nicole Carroll.