In 1909, Edward Payson Weston walked from New York to San Francisco, covering around 40 miles a day and greeted by wildly cheering audiences in every city. The New York Times called it the "first bona-fide walk . . . across the American continent," and eagerly chronicled a journey in which Weston was beset by fatigue, mosquitos, vicious headwinds, and brutal heat. He was 70 years old. In The Last Great Walk, journalist Wayne Curtis...