S.D. Codified Laws § 1-6-4
The state flag or banner shall consist of 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.
SDCL 1-6-4