The EMC E1 was an early passenger-train diesel locomotive developing 1,800 hp, with an A1A-A1Awheel arrangement, and manufactured by Electro-Motive Corporation of La Grange, Illinois. They were built during 1937 and 1938 for the Atchison, Topeka and Santa Fe Railway for a new generation of diesel-powered streamlined trains. 8 cab-equipped lead A units and three cabless booster B units were built. The initial three locomotives were AB pairs built to haul the Santa Fe's Super Chief diesel streamliners, while the others were built as single A units to haul shorter trains. The locomotives were diesel-electrics with two 900 hp (670 kW) Winton 201-A engines each, with each engine driving its own generator to power the traction motors. The E1 was the second model in a long line of passenger diesels of similar design known as EMD E-units. All Winton 201A-engined Santa Fe passenger units, including the E1s, were extensively rebuilt into the 80-class E8M engines in 1952–53. These were similar to production E8 models, but derated to 2,000 hp so as not to burn out the early traction (axle) motors (which were reused).