Southern Pacific No. 2521 was built by the Baldwin Locomotive Works in Schenectady, New York, and delivered to the Southern Pacific Railroad in 1907. In its lifetime, this historic engine logged an estimated 2.5 million miles hauling passengers and freight through the southern United States. S.P. No. 2521 served as a main-line hauler in the Yuma area for more than forty years before steam technology was replaced by the modern diesel engine. The Southern Pacific Railroad donated the locomotive to the city of Yuma in April 1957. S.P. No. 2521 is 79 feet long and weighs more than 194 tons, 388,000 pounds, and could haul 35 loaded boxcars at up to 40 miles per hour.