S.D. Codified Laws § 7-1-26
Beginning at a point where the township line between townships one hundred seventeen and one hundred eighteen north intersects the eastern boundary line of the State of South Dakota, thence west and along said township line to the southwest corner of township one hundred eighteen north of range fifty west of the fifth principal meridian; thence north and along the range line between ranges fifty and fifty-one to the township line between townships one hundred nineteen and one hundred twenty north; thence west and along said township line, crossing the Sisseton and Wahpeton Indian Reservation in the same course, to the southwest corner of section nineteen, township one hundred twenty north of range fifty-two west; thence north and along the range line between ranges fifty-two and fifty-three west to the township line between townships one hundred twenty-one and one hundred twenty-two north, according to the survey of the former Sisseton and Wahpeton Indian Reservation; thence east and along said township line to the former easterly boundary of said reservation; thence northeasterly along said former boundary to the township line between townships one hundred twenty-one and one hundred twenty-two north, outside of said former reservation; thence east and along said township line to the eastern boundary of the State of South Dakota; thence southeasterly and south along said state line to the place of beginning.
SDCL 7-1-26