What does "South Dakota" mean?
"Dakota" is the word for "friend" in the Native American Sioux language. All State Name Origins
President James Buchanan signed the bill creating the Dakota Territory in 1861. The Dakota Territory originally included the area covered today by North and South Dakota as well as Montana and Wyoming. On November 2, 1889, both North and South Dakota were admitted to the Union, becoming the 39th and 40th states. Dates of Statehood