S.D. Codified Laws § 31-4-192 (2026)
The state trunk highway system includes the following in Grant and Roberts counties: From U.S. Highway 12 southeast of Summit south of the northeast corner of section twenty-five, township one hundred twenty-one north, range fifty west, thence north to State Highway 15 in Wilmont near the northeast corner of section one, township one hundred twenty-two north, range fifty west.
Source: SL 1984, ch 209 , § 65.