The Rock Island Railroad was very important to Canadian County from 1890-1980. El Reno was the Southern Division Headquarters or Rock Island RR and at its peak had 1,200 employees. The first headquarters was south of the present depot near the flour mills. The depot where the Museum is today was constructed in 1906. Passenger trains started running in 1907 with as many as 23 passenger trains a day coming in and out of the depot. In 1908 plans were made for a 40-foot addition on the south end and a 17-foot addition on the north end. In 1908 freight yards and repair facilities were opened in El Reno.
Passenger service was discontinued in November of 1967. In 1970 the depot was leased and later purchased by the Canadian County Historical Society for a county museum.
The Rock Island Depot houses the main Museum of the Canadian County Historical Society. The Depot’s exhibits include railroad memorabilia, early pioneers and settlers, Fort Reno, Darlington, and Indian exhibits.