SDCL § 31-4-236: State Highway 391 from Nebraska to U.S. Highway 18.

The state trunk highway system includes the following in Oglala Lakota County:

From a point on the Nebraska state line near the northwest corner of section twenty-four, township thirty-five north, range forty-two west, thence north to U.S. Highway 18 near the northeast corner of section two, township thirty-five north, range forty-two west.