S.D. Codified Laws § 31-20-8
Whenever the State of South Dakota or any county of said state has, before March 18, 1957, received a conveyance of a parcel of Indian allotment land for highway right-of-way purposes by an instrument purporting to convey fee title thereto the county or state, as the case may be, is hereby authorized to reconvey the fee title to the United States of America if the parcel is no longer used or needed for right-of-way purposes. However, in case any of said parcel is still needed for right-of-way purposes said reconveyance, if made, shall be made subject to an easement being reserved for right-of-way purposes in the grantor. Any such deed running to the United States shall recite that same is in trust for any Indian or tribe entitled thereto. Such conveyance shall be to enable a fee patent to be issued to Indian owner subject to the easement for right-of-way.
SDCL 31-20-8