Like many other steeplecab electric locomotives in the USA, Milwaukee Road No. 10000 was ordered for service in special places which were electrified with DC via overhead lines. In this case, a switcher was needed for the yard at Great Falls, Montana. It was delivered by General Electric in 1915 and designated class ES-1 by the operator. Power came from four 79 hp traction motors and the locomotive weighed roughly 45 short tons. In March 1939 it was renumbered to E85, but it was retired only eight months later.