Atchison, Topeka & Santa Fe 3751 is a class 3751 4-8-4 steam locomotive built in 1927 by the Baldwin Locomotive Works in Eddystone (Philadelphia), Pennsylvania for the Atchison, Topeka & Santa Fe Railway (ATSF). 3751 was the first 4-8-4 steam locomotive built for the Santa Fe and was referenced in documentation as type: "Heavy Mountain", "New Mountain", or "Mountain 4-wheel trailer". No. 3751 served in passenger duties until being retired in 1953.