North and South Dakota were a single territory until 1889. Dakota was named for the Dakota, Sioux tribe which lived in the region it is the Sioux word for "friends" or "allies".

South Dakota's original flag was adopted in 1909 and had a blue background with an image of the sun on the front and the state's seal on the back. In 1963, the flag was revised to show the state's seal with the sun's rays eminating from it. In the revised flag the back or reverse side was left blank. The words "SOUTH DAKOTA" and "THE MOUNT RUSHMORE STATE" encircle the image. South Dakota's state seal shows a farmer plowing a field, a river, forests, mountains, a steamboat, and the motto, "Under God the People Rule."