The state trunk highway system includes the following in Charles Mix, Bon Homme, Yankton, Clay, and Union counties:
From a point on U.S. Highway 18 in the southeast quarter of section four, township ninety-five north, range sixty-five west, thence east via Wagner, Irene, and Beresford to the Iowa state line near the northeast corner of section fifteen, township ninety-five north, range forty-eight west.