The Chicago, Milwaukee and St. Paul Depot in Yankton, South Dakota was built in 1905 by the Chicago, Milwaukee, St. Paul and Pacific Railroad (otherwise known as The Milwaukee Road). Prior to the 1870s, Yankton was served by steamboats along the Missouri River. As service declined, railroads took over to serve the communities in South Dakota. In the late 1870s, the Dakota Southern Railroad entered Yankton. Shortly afterward, the Dakota Southern was bought by The Milwaukee Road. The Milwaukee Road then expanded westward toward Rapid City, South Dakota and the Black Hills.