South Dakota Highway 63 (SD 63) is a 167.455-mile (269.493 km) state highway in central South Dakota, United States, that connects U.S. Route 18 (US 18) south-southeast of Parmelee with the North Dakota state line north of McLaughlin. Portions of SD 63 north of US 14/SD 34 west of Hayes are part of the Lewis and Clark Trail. The segment of the highway, from US 14/SD 34 just west of Hayes, to US 212 west of Eagle Butte, is part of the . The portion of the highway, from just north of the intersection with SD 44 to a point approximately 5 miles (8.0 km) south of Belvidere, is a dirt road.