ALCO, or "American Locomotive Company" was; as name may suggest, a manufacturer of american railway locomotives.

They are most famous for their large "super power" steam locomotives, however, with the advent of deisel-electric traction, Alco and contemporary engine builders would bring along the first generation of deisel traction. They would not, however, manage to out-compete the mew innovators on the block; GM(EMD) and GE. Alco and other legacy builders sutch Baldwin-Lima-Hamilton would all eventually go defunct in the late 20th century.