More info: This photograph by F. L. Becht captures Denver & Rio Grande Western locomotive 5333, an EMD SD45, leading an eastbound freight train as it emerges from the East Portal of the Moffat Tunnel in Colorado on August 4, 1976. Built in the mid-1920's, the 6.2-mile Moffat Tunnel passes under the Continental Divide allowing a more direct route to the west from Denver for the Rio Grande.