Photographer Nell Dickerson fondly recalls childhood nights on the sleeping porch of her grandparents’ Mississippi Delta home—the sounds of katydids, cicadas, and tree frogs, the merciful breeze from the overhead fan. But during the heat of the day, the family sought refuge indoors, leaving the dog to his lonely vigil. “I felt like he understood that the porch was the gateway between inside and outside and that it was his duty to keep sentry there in case someone wanted to pass,” she recalls. For eight years, Dickerson traveled across the South taking portraits of dogs committed to the deep-seated tradition of watching the world. Those photographs comprise her latest book, Porch Dogs.