U.S. Route 18 in South Dakota

U.S. Highway 18
US 18 highlighted in red
Route information
Maintained by SDDOT
Length	451.88 mi[1] (727.23 km)
Existed	1926–present
Major junctions
West end	US 18 at the Wyoming state line near Edgemont
Major intersections	US 385 from Hot Springs to Oelrichs US 83 in Mission US 183 from Jordan Junction to Colome US 281 from near Fairfax to near Armour US 81 near Freeman I-29 near Worthing
East end	US 18 at the Iowa state line near Canton
Location
Country	United States
State	South Dakota
Counties	Fall River, Oglala Lakota, Bennett, Todd, Tripp, Gregory, Charles Mix, Douglas, Hutchinson, Turner, Lincoln
Highway system
United States Numbered Highway System List Special Divided South Dakota State Trunk Highway System Interstate US State
← SD 17 → SD 18

U.S. Highway 18 (US 18) is a part of the United States Numbered Highway System that travels from Orin, Wyoming, to Milwaukee, Wisconsin. In the state of South Dakota, US 18 runs from the Wyoming border east to the Iowa border. The highway runs parallel to the state's southern border with Nebraska, and at one point, near Fairfax, US 18 comes within one mile to the Nebraska border.