The Alco RS Series refers to a line of diesel-electric locomotives produced by the American Locomotive Company (ALCO) from the late 1940s to the early 1960s. These locomotives were designed for road switching and freight service, featuring a robust construction and a powerful engine that made them suitable for various rail operations. The RS Series includes several models, such as the RS-1, RS-2, and RS-3, each with different specifications and capabilities. Known for their versatility, these locomotives were widely used by numerous railroads across North America and remain popular among rail enthusiasts and preservation groups today.