Union Pacific Steam Engine #1242, nicknamed "Old Sadie," is the oldest coal burning steam locomotive in Wyoming. Built in December 1890 by Cooke Locomotive & Machine Works of Petterson, NJ, the Ten-Wheel engine ran the 44 mile Walcott-Saratoga-Encampment branch line from November 1, 1921 until its last trip on May 15, 1954 with Union Pacific engineer Floyd Young, Sr. Originally built in 1908 to haul copper from the Encampment area, the line soon shifted to carrying livestock and forest products to the Union Pacific main line connection at Walcott Junction, 127 miles west of Cheyenne, after the mines closed. Union Pacific donated the retired locomotive to the City of Cheyenne in 1955. After World War II, efficient diesel locomotives gradually replaced steam locomotives, whose heavy demands for fuel, water, and labor-intensive maintenance led to their decline, although Wyoming remained a late stronghold where the big engines ran their last miles in 1959. Union Pacific's heritage steam operations are still maintained in Cheyenne in a portion of the old roundhouse in the rail yard.