UP 844 was the last steam locomotive delivered to the Union Pacific Railroad, constructed as a member of the FEF-3 class of 4-8-4 "Northern" type locomotives. Upon its entry into service, the locomotive spent most of its career pulling a variety of passenger trains, such as the Overland Limited, Los Angeles Limited, Portland Rose and Challenger. From 1957 to 1959, UP 844 was reassigned to fast freight service in Nebraska when diesel-electric locomotives took over passenger service.

After commercial steam operations ended in 1959, the 844 and the rest of the FEF-3 class was placed into storage. Saved from scrapping in 1960, No. 844 was chosen for rebuilding and is now used on company and public excursion trains, along with revenue freight during ferry moves.