The current flag of South Dakota was adopted in 1992 to represent the U.S. state of South Dakota. It consists of a field of sky blue charged with a version (in navy blue on white) of the state seal in the center, surrounded by gold triangles representing the sun's rays, surrounded in turn by inscriptions in gold sans-serif capitals of "south dakota" on top and "the mount rushmore state" (the state nickname) on the bottom. The sun represents the common weather in South Dakota.
The first state flag was designed and adopted in 1909. This original flag was bi-faced, with a sun motif on one side and the state seal on the other. A redesign in 1963 embedded the state seal inside the original flag's sun motif. The inscription on the bottom was "the sunshine state" before it was changed in 1992.
The 2025 South Dakota Codified Laws, Title 1, Chapter 6, § 1-6-4, defines the state flag as follows:
...a field of sky-blue one and two-thirds as long as it is wide.
Centered on such field shall be the great seal of South Dakota made in conformity with the terms of the Constitution, which shall be four-ninths the width of the flag in diameter. The seal shall be on a white background with the seal outlined in dark blue or, in the alternative, shall be on a sky-blue background with the seal outlined in dark blue thereon.
Surrounding the seal in gold shall be a serrated sun whose extreme width shall be five-ninths the width of the flag.
The words "South Dakota" symmetrically arranged to conform to the circle of the sun and seal shall appear in gold letters one-eighteenth the width of the field above the sun and seal and the words "The Mount Rushmore State" in like-sized gold letters and in like arrangement shall appear below the sun and seal.
Flags designed of such material as may be provident for outdoor use need have no fringe but flags for indoor and display usage shall have a golden fringe one-eighteenth the width of the flag on the three sides other than the hoist.
The 2025 South Dakota Codified Laws, Title 1, Chapter 6, § 1-6-2, defines that the state seal shall consist of:
Circular border: "State of South Dakota" written at top and "Great Seal 1889" at bottom, with stars on either side
Left foreground: Smelting furnace, hoist house, mill, and dump near a grove on the riverbank
Left background: Three ranges of hills
Right foreground: Farmer holding a breaking plow drawn by two horses
Right background: Pasture with grazing cattle and a field of corn; hills in the distance
Center: River flowing into the distance with a steamboat; shrubbery on riverbanks
Top: State motto, "Under God the People Rule"
On June 21, 1883 the people of Huron gathered and came up with the idea of a Dakota state flag. The flags were planned to be raised on July 4, and hang out till the election of that year. They were described as bearing the words: "State of Dakota." In June, Captain Lyons was sailing though Yankton when he flew a state flag from the masthead of his boat. It bore the motto "C. A. Lyons & Co."
The first flag of South Dakota was designed by Ida McNeil in 1909. Ernest May, a state legislator from Deadwood, approached South Dakota Department of History superintendent Doane Robinson about the lack of a state flag. McNeil was then a legislative reference librarian at the state department. McNeil later recalled that during their meeting, Robinson turned to her and told May, "Miss Anding will make you a flag".