Union Pacific 844 is a 4-8-4 "Northern" type steam locomotive built by the American Locomotive Company in December 1944 for the Union Pacific Railroad. Constructed as a member of the FEF-3 class of 4-8-4's, the 844 was the last steam locomotive delivered to Union Pacific. Though the FEF-3 class was originally built for high-speed passenger work, 844 and the rest of the FEF-3 class were pressed into a variety of dual-service work. While commercial Union Pacific steam operations ended in the late 1950s, 844 was retained by the railroad for special activities. Today, it is one of UP's oldest serving locomotives,^[1] as well as the only steam locomotive never retired by a North American Class I railroad.^[2]