S.D. Codified Laws § 37-1-5
Any person doing business in this state and engaged in the production, manufacture, or purchase of any commodity or product in general use, who, with intent and for the purpose of destroying competition by any regular established dealer in such commodity or product, shall discriminate between different sections, communities, or first and second class municipalities of this state by paying for such commodity or product a higher price in one section, community, or municipality than such person or corporation is at the same time paying for such commodity or product in another section, community, or municipality within the state, after equalizing the distance from the point of purchase and transportation charges therefrom, and the grade and quality thereof, shall be deemed guilty of unfair discrimination.
SDCL 37-1-5