SDCL § 31-4-181: U.S. Highway 85 from Wyoming to North Dakota.

The state trunk highway system includes the following in Lawrence, Butte, and Harding counties:

(1) From a point on the Wyoming state line on the west line of section thirty-one, township three north, range one east, thence northeasterly to Cheyenne Crossing in the northwest quarter of section twenty-two, township four north, range two east;

(2) From a point on U.S. Highway 14 Alternate in Lead in section thirty-two, township five north, range three east, thence northeasterly via Lead and Deadwood to U.S. Highway 14 Alternate in Deadwood near the southwest corner of section twenty-three, township five north, range three east;

(3) From a point on U.S. Highway 14 Alternate in Deadwood near the southwest corner of section thirteen, township five north, range three east, thence northwesterly to Interstate Highway 90 east of Spearfish in section fifteen, township six north, range three east;

(4) From a point on Interstate Highway 90 north of Spearfish in section thirty-four, township seven north, range two east, thence north via Belle Fourche and Buffalo to the North Dakota state line.