On May 26, 1934, a shimmering silver locomotive pulled out of Denver's Union Station, bound for Chicago. Unlike any train seen before, the Zephyr was a streamliner powered by a revolutionary compact diesel engine, able to cover 1,015 miles in 15 hours. By the 1940s, fleets of streamliners crisscrossed the United States, but within two decades, their era was over, routes discontinued, and the cars sold off to Canada and Japan.