A 3,000-mile rail journey traces the Transcontinental Railroad from the Atlantic to the Pacific, crossing four time zones and twelve states. The trip starts at the Baltimore and Ohio Railroad Museum among some of the country's oldest steam locomotives, then moves through Grand Central Terminal in New York and the freight yards of Chicago, where the film covers railroads' role in the Civil War. Boarding Amtrak's California Zephyr, the journey stops in Omaha to trace the Union Pacific's origins and in Denver to examine a mining railroad's impact on Native American communities. Through the Rockies to Utah, the film visits the site marking the line's 1869 completion, then reaches Truckee to look at the Chinese laborers who built the route through the Sierra Nevada. It ends in Sacramento with a boat crossing to San Francisco. Location shooting and archival detail carry the history, treating the railroad as both an engineering feat and a story of the people who paid for it.