Colorado River State Historic Park in Yuma preserves the former Yuma Quartermaster Depot, established by the U.S. Army in 1864 as a major supply center for frontier posts across the Southwest. Supplies traveled by sea to the Gulf of California, then by river boat up the Colorado to Yuma, where they were transferred to steamboats and mule-team wagons; at its height, the depot housed as many as 900 mules. Its importance declined after the Southern Pacific Railroad reached Yuma in 1877 and Tucson in 1880, and the depot closed. Five original buildings survive, connecting Yuma’s military, transportation, and river history through preserved structures and exhibits.