South Dakota Highway 15

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Highway 15
Map of South Dakota with SD 15 in red
Route information
Maintained by SDDOT
Length	67.562 mi[1] (108.730 km)
Existed	c. 1926[citation needed]–present
Major junctions
South end	SD 28 west of Toronto
Major intersections	SD 22 in Clear Lake US 212 from north of Altamont to near Revillo SD 20 near Revillo SD 20 / SD 158 near La Bolt US 12 in Milbank I-29 / US 81 near Summit
North end	CR 17 / CR 34 north of Summit
Location
Country	United States
State	South Dakota
Counties	Deuel Grant Roberts
Highway system
South Dakota State Trunk Highway System Interstate US State
← US 14 → US 16

South Dakota Highway 15 (SD 15) is a 67.562-mile-long (108.730 km) state highway in the northeastern South Dakota, United States. It connects Clear Lake, Milbank, and Wilmot.

SD 15 originally traveled from the Nebraska state line to the North Dakota state line. It followed what would eventually become U.S. Route 77 (US 77), which had been designated before 1931. Part of its path went north from Wilmot to Sisseton, then north to Hammer, along US 81's former path, west to Claire City, north to the North Dakota state line north of Claire City, where it met North Dakota Highway 18 (ND 18).

The segment from Sisseton to Hammer was redesignated as SD 127; the segment from Hammer to Claire City was redesignated as SD 106. From Claire City to North Dakota became SD 25. Part of the highway in the Wilmot area was redesignated as SD 15A.