The Delaware, Lackawanna & Western's Number 3001 Diesel-Electric Locomotive, probably 1926

Diesel-electric locomotives, introduced on American railroads in the 1920s, offered several advantages over their steam-powered counterparts. They used less fuel, required less maintenance, and could be operated by smaller crews. Many early diesel-electrics proved themselves in yard service, like this unit switching cars at a marine terminal on the Delaware, Lackawanna & Western Railroad.