Plymouth locomotives were first built in 1910 by the J.D. Fate Company, which became Fate-Root-Heath in 1919. All early locomotives were powered by gasoline-burning internal combustion engines, but in 1927 the first diesel was produced. The company changed its name to match its locomotive plant in the late 1950s, becoming Plymouth Locomotive Works; in the late 1970s, it became Plymouth Industries.
Plymouth was one of the world's most prolific builders of small industrial locomotives, with over 7,500 constructed of which 1,700 are believed to still be in active use, some of which are over 50 years old. Almost all Plymouth locomotives were under 25 tons. They produced locomotives in most rail gauges, mostly with mechanical torque converter transmissions.