The ALCO RS-2 is a 1,500–1,600 horsepower (1,100–1,200 kW) B-B diesel-electric locomotive built by the American Locomotive Company (ALCO) from 1946 to 1950. ALCO introduced the model after World War II as an improvement on the ALCO RS-1. Between 1946 and 1950, 377 examples of the RS-2 were built, primarily for American and Canadian customers. ALCO discontinued the RS-2 in 1950 in favor of the very similar RS-3, which was significantly more popular. Several examples have been preserved.