This design for the flag of South Dakota was meant to be quite different from other flags, as it has a white background.
The blue and white represent the United States. The green represents the state of South Dakota. My original idea for the design had dark blue instead of light blue, but I think the light blue looks better. The yellow mountain represents the Black Hills and Black Hills gold. Also, the mountain is in the shape of Mt. Rushmore, a national symbol of the United States.