The Union Pacific FEF (Four Eight Four), along with the GS-4 is easily one of the most recognizable US steam prototypes still in operation today. The FEF-3 series of steam locomotives was delivered in 1944 and were the last, and some of the largest, steam locomotives delivered for use by the Union Pacific. Operated solely by the Union Pacific, the FEF’s (sometimes referred to as “Northerns”, due to the NP’s being the first to build steam locomotives with the 4-8-4 wheel arrangement) were intended primarily to be passenger locomotives but the UP’s large fleet of available diesels meant that the FEF’s were put to work in secondary passenger and fast freight service.
