This clean, cheap, faster, and more economical locomotive was one of the six used only on the Denver & Rio Grande Western, replacing the steam locomotives. The role for this locomotive was to pull the California Zephyr between Illinois and California, along with the Western Pacific and the Chicago, Burlington & Quincy Expedition Flyer. The purpose was to connect Chicago, IL, with the Golden Gate International Expedition in San Francisco, CA. There was a lot of demand even after the completion of the Golden Gate Bridge. New streamlined cars were added. After WWII, railroads started to replace steam locomotives with diesel-electric locomotives. In 1949, three of the railroads that were partnered were replaced by a new train. A set called the California Zephyr replaced the Expedition. Flyer. This train set provided dome cars to let passengers view the scenery more conveniently. The F9s would have more horsepower than the F7s. They were more convenient for climbing hills. B units were used as locomotives without a cab, giving the train more power. In the 1960's as newer modes of transportation such as commercial airlines and road transportation replaced a lot of the business provided by railroad carriers. The final trip for the California Zephyr was in 1970. Amtrak was coming into play in 1971 to keep passenger service when needed by rail. Amtrak wanted a route to operate between Denver, CO, and Salt Lake City, UT on the Rio Grande Mainline. But because Amtrak might improve later on, Rio Grande disapproved of their request. Rio Grande refused to merge with Amtrak and continued operating on its route. Three days a week, the Rio Grande Zephyr operated round-trip between Colorado and Utah except on Wednesday. There were no more sleepers due to it being a day trip
only. Due to struggling financially, the last non-Amtrak intercity train Rio Grande Zephyr, was discontinued in 1983. Amtrak replaced the route between Colorado and Utah, operating currently as the California Zephyr. Denver & Rio Grande Western #5771 was out of business until needed for freight service or operating for the Ski Train in 1984 from Denver to Winter Park and finally retired in the fall of this year. Three F9 units were stored temporarily at the shops in Denver, CO, with the merger of Southern Pacific in 1988. In 1996, Southern Pacific merged with the Union Pacific, and they donated Denver & Rio Grande Western #4771 to the Colorado Railroad Museum.