SDCL § 31-4-161: State Highway 40 from U.S. Highway 16 Alternate to Cheyenne River.

The state trunk highway system includes the following in Pennington and Custer counties:

(1) From a point on U.S. Highway 16 Alternate in Keystone in section eight, township two south, range six east, thence southeasterly via Keystone to State Highway 79 south of the northeast corner of section thirty-one, township two south, range eight east;

(2) From a point on State Highway 79 near the northeast corner of section thirty-one, township two south, range eight east, thence southeasterly to the south end of the Cheyenne River Bridge in section twenty-five, township four south, range ten east.