On his seventieth birthday in 1909, a slim man with a shock of white hair, a walrus mustache, and a spring in his step faced west from Park Row in Manhattan and started walking. By the time Edward Payson Weston was finished, he was in San Francisco, having trekked 3,895 miles in 104 days. Weston's first epic walk across America transcended sport. He was "everyman" in a stirring battle against the elements and exhaustion, tramping along...