S.D. Codified Laws § 37-1-4
Any person doing business in this state, and engaged in the production, manufacture, or distribution of any commodity in general use, who intentionally, for the purpose of destroying the competition of any regular established dealer in such commodity or to prevent the competition of any person who in good faith intends and attempts to become such dealer, shall discriminate between different sections, communities, or first and second class municipalities of this state by selling such commodity at a lower rate in one section, community, or municipality, or any portion thereof than such person or corporation charges for such commodity in another section, community, or municipality, after equalizing the distance from the point of production, manufacture, or distribution and freight rates therefrom, shall be deemed guilty of unfair discrimination.
SDCL 37-1-4