South Dakota Highway 15
Route of SD 15 (in red)
|Maintained by SDDOT|
|Length:||79.430 mi (127.830 km)|
|Existed:||1926 (approx.) – present|
|South end:||SD 28 west of Toronto|
|North end:||I‑29 west of Wilmot|
South Dakota Highway 15 is a state route that largely runs north to south across northeastern South Dakota. The northern terminus is at the junction with Interstate 29 west of Wilmot (exit 213) and the southern terminus is at I-29 west of Toronto (exit 150). It is 78 miles (129 kilometers) in length.
The route of SD 15 is defined in South Dakota Codified Laws § 31-4-137.
South Dakota 15, when designated in the mid-1920s, ran north to south across the entire state, on the road known as the King of Trails. The extension of U.S. Highway 77 in 1930 largely replaced the numbering of SD 15, from Milbank to Sioux City. The northern portion of the route, from U.S. Highway 12 to the North Dakota border north of Claire City, remained in place.
In the early 1950s, changes were made to the southern end. SD 15 was rerouted so the south end was at Milbank; it then went north to Hartford Beach, then west through Wilmot to U.S. Highway 81, before heading north again. The old alignment from Wilmot to U.S. 12 was designated at South Dakota Highway 15A.
In 1976, the segment of SD 15 from the North Dakota border to Claire City was made part of a realigned South Dakota Highway 25, and the segment from Claire City to U.S. 81 near Claire City was designated as South Dakota Highway 106. At that point, the northern terminus was located at U.S. 81 west of Wilmot.
After U.S. 77 was deleted in the early 1980s, SD 15 was extended south along the former's alignment from Milbank, to the present end at I-29 west of Toronto.
|Deuel||0.000||0.000||SD 28 – Toronto, Estelline|
|Clear Lake||12.036||19.370||SD 22 – Castlewood, Canby, MN|
|22.179||35.694||US 212 west – Kranzburg||Southern end of US 212 concurrency|
|26.978||43.417||US 212 east – Dawson, MN||Northern end of US 212 concurrency|
|Grant||32.542||52.371||SD 20 east – Madison, MN||Southern end of SD 20 concurrency|
|39.564||63.672||SD 20 west / SD 158 east – Stockholm||Northern end of SD 20 concurrency, western terminus of SD 158|
|Milbank||46.727||75.200||US 12 – Twin Brooks, Big Stone City|
|Roberts||60.033||96.614||SD 109 south – Big Stone City|
|Wilmot||71.529||115.115||SD 123 south|
|78.364||126.115||I‑29 – Fargo, ND, Sioux Falls|
|1.000 mi = 1.609 km; 1.000 km = 0.621 mi
South Dakota Highway 15A was a short state route in northeastern South Dakota. This route was originally part of SD 15. In the early 1950s, the alignment of SD 15 was adjusted to add a segment between Wilmot and Milbank. The old alignment, between Wilmot and U.S. Highway 12, was designated as SD 15A. In 1976, when many of the suffixed state routes were eliminated, this route was redesignated as South Dakota Highway 123.