SDCL § 31-4-190: State Highway 109 from U.S. Highway 12 to State Highway 15.

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

From a point on U.S. Highway 12 in Big Stone City in the northwest quarter of section seventeen, township one hundred twenty-one north, range forty-six west, thence northwest to State Highway 15 east of Hartford Beach near the northwest corner of section twelve, township one hundred twenty-two north, range forty-eight west.