The generator and oil buildings were constructed around 1910. The railroad needed electricity for its West Yellowstone operations and facilities, but the closest available power was a great distance away. So the Union Pacific Railroad built its own generating plant, consisting of the oil and generator buildings. These facilities constituted the first power plant in town, and the town had access to the extra power which was generated. The initial structures matched the rock work of the depot. The generator building was soon expanded to accommodate the larger equipment needed to supply the expanding railroad facilities. A Mercedes Benz diesel generator replaced the original gas generator.
In the late 1920s, Gilbert Stanley Underwood designed a new decorative cladding for both of these buildings so they would more closely resemble the Dining Lodge from which they were separated by only yards. The exterior walls were faced with bark-covered wood, and the corners were embellished with massive decorative stone piers. The original stone buildings are still there - encased by this more recent façade. The Mercedes Benz generator remains in its original location, inside the generator building.