The film is based in large part on the real Yosemite Valley Railroad, which ran from 1907 to 1945 outside Yosemite National Park and though that short line's visual presence has been totally erased from history, the film's designer and locations team did a breathtaking job of bringing this long-lost railroad back to cinematic life. The central character is loosely based on the real-life 18-year-old John McFadden of Pasadena, who in 1945 was alleged to have a plan to save the railroad from being scrapped. Unfortunately, McFadden failed and the railroad was lost.