SDCL § 31-4-137: State Highway 15 from State Highway 28 to Interstate Highway 29.

The state trunk highway system includes the following in Deuel, Grant, and Roberts counties:

(1) From a point on State Highway 28 west of Toronto near the southwest corner of section twenty-three, township one hundred thirteen north, range forty-nine west, thence north via Clear Lake and Altamont to U.S. Highway 212 north of Altamont near the southeast corner of section thirty-four, township one hundred seventeen north, range forty-nine west;

(2) From a point on U.S. Highway 212 south of Milbank near the southwest corner of section eighteen, township one hundred seventeen north, range forty-eight west, thence north to State Highway 20 south of Milbank near the southwest corner of section nineteen, township one hundred eighteen north, range forty-eight west;

(3) From a point on State Highway 20 south of Milbank near the southwest corner of section eighteen, township one hundred nineteen north, range forty-eight west, thence north and west via Milbank to Interstate Highway 29 near the west line of section twenty-six, township one hundred twenty-three north, range fifty-one west.