Area code 605 is the only area code for the entire state of South Dakota. Established in 1947, it has remained unchanged despite population growth. The area code covers everything from the Black Hills to Sioux Falls and Rapid City. It represents the wide-open spaces, rural communities, and Mount Rushmore’s home state. Seven-digit dialing is typical statewide. Area code 605 is a strong emblem of South Dakota’s unity, rugged frontier heritage, and natural beauty, often proudly displayed as a state symbol.