U.S. Route 83 (US 83) is a major north–south United States Numbered Highway that extends 1,885 miles (3,034 km) in the central United States. Only four other north–south routes are longer: US 1, US 41, US 59, and US 87, while US 83 follows a straighter north-south path than all of these. Nearly half of its mileage is in the state of Texas. The highway's northern terminus is north of Westhope, North Dakota, at the Canadian border, where it continues as Manitoba Highway 83 (PTH 83). The southern terminus is at the Veterans International Bridge in Brownsville, Texas. Together, US 83 and PTH 83 form a continuously numbered north-south highway with a combined distance of 3,450 kilometres (2,140 mi).
U.S. Highway 16 (US 16) is an east–west United States Numbered Highway between Rapid City, South Dakota, and Yellowstone National Park in Wyoming. The highway's eastern terminus is at a junction with Interstate 90 (I-90)/US 14, concurrent with I-190, in Rapid City. The western terminus is the east entrance to Yellowstone National Park, concurrent with US 14 and US 20. US 16 used to extend all the way to Michigan but has been truncated in favor of I-90 and I-96.
U.S. Highway 18 (US 18) is an east–west United States Numbered Highway in the Midwestern United States. The western terminus is in Orin, Wyoming, at an interchange with Interstate 25 (I-25). Its eastern terminus is in downtown Milwaukee, Wisconsin. However, US 18 runs concurrent with other U.S. Highways from its western terminus to Mule Creek Junction, Wyoming. US 18 is one of the original U.S. Highways of 1926. The US 18 designation was originally proposed for a road in Michigan from Grand Haven east to Detroit. This roadway was eventually designated as US 16.
U.S. Route 212 (US 212) is a spur of US 12. It runs for 949 miles (1,527 km) from Yellowstone National Park to Minnesota Highway 62 at Edina, Minnesota. It does not intersect US 12 now, but it once had an eastern terminus at US 12 in St. Paul, Minnesota. US 212 passes through the states of Minnesota, South Dakota, Wyoming, and Montana. It goes through the cities of Watertown, South Dakota and Billings, Montana.
South Dakota Highway 87 (SD 87) is a 37.894-mile-long (60.984 km) state highway in the southwestern part of the U.S. state of South Dakota. It travels through the Black Hills region. The highway's southern terminus is at an intersection with U.S. Route 385 (US 385), about 6 miles (9.7 km) southeast of Pringle, within the southwestern part of Wind Cave National Park. Its northern terminus is at an intersection with US 16/US 385 about 3 miles (4.8 km) south-southwest of Hill City, within the east-central part of the Black Hills National Forest.
South Dakota Highway 471 (SD 471) is a 21.981-mile (35.375 km) state highway in western Fall River, South Dakota, United States, that connects Highway 71 (SD 71), southeast of Rumford, with U.S. Route 18 (US 18), in Edgemont.
South Dakota Highway 43 (SD 43) is a 1.131-mile-long (1.820 km) state highway that exists entirely in the southern part of Gregory County in the southern part of the U.S. state of South Dakota. It begins as an extension of Nebraska Highway 11 (N-11) at the Nebraska state line south of Fairfax. It travels northwest to an intersection with U.S. Route 18 (US 18) south-southwest of the town.
South Dakota Highway 47 is a state route that runs north to south across the central portion of South Dakota. It begins at an unnumbered highway at the North Dakota border north of Eureka, and ends at the Nebraska border, where it becomes Nebraska Highway 137. It is just under 241 miles (388 km) in length.
South Dakota Highway 48 is a 12.462-mile (20.056 km) state highway in Union County, South Dakota, United States, that begins at Interstate 29, about 2.5 miles (4.0 km) west of Spink, and becomes Big Sioux River Road, formerly Iowa Highway 403, northwest of Akron, Iowa.
South Dakota Highway 49 is a 35.134-mile (56.543 km) long state route that runs north to south in south-central South Dakota. It begins at a junction with South Dakota Highway 47 just south of the White River, and terminates at the junction of U.S. Highway 18 and U.S. Highway 183 in Colome.
South Dakota Highway 53 is a state route that runs north to south across south central South Dakota. It consists of two separate segments:
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.
South Dakota Highway 50 is a state route serving south central and southeast South Dakota. The current alignment begins at the junction of South Dakota Highway 34 at "Lee's Corner" east of Fort Thompson, and ends at the Iowa border near Richland, where it continues as Iowa Highway 3. It is about 212 miles (341 km) in length.
South Dakota Highway 30 (SD 30) is a 17.077-mile-long (27.483 km) state highway in the east-central part of the U.S. state of South Dakota. It connects the north-central part of Brookings with the northeastern part of it.
South Dakota Highway 34 is a state route that runs parallel to Interstate 90 across the entire state of South Dakota. It begins at the Wyoming border west of Belle Fourche, as a continuation of Wyoming Highway 24 (WYO 24). The eastern terminus is at the Minnesota border east of Egan, or southwest of Airlie, Minnesota, where it continues as Minnesota State Highway 30 (MN 30). It is just over 419 miles (674 km) in length, making it the longest state highway in South Dakota.
South Dakota Highway 36 is an east–west state route located in southwest South Dakota. It begins at the junction of U.S. Route 16A on the eastern edge of Custer State Park, and ends at South Dakota Highway 79 just south of Hermosa. It is slightly over nine miles (14 km) in length.
South Dakota Highway 37 is a state route that runs across eastern South Dakota. It begins at the Nebraska border northeast of Niobrara, Nebraska, as a continuation of Nebraska Highway 14. It runs to the North Dakota border north of Hecla, where it continues as North Dakota Highway 1. It is 242 miles (389 km) in length.
South Dakota Highway 42 (SD 42) is a segmented state highway in southeastern South Dakota, United States. The first segment is a six-mile-long (9.7 km) highway in Aurora County. The second and longest is 60 miles (97 km) long and connects Ethan and Sioux Falls. The final segment connects Sioux Falls to Iowa Highway 9 southeast of Rowena.
South Dakota Highway 1804 (SD 1804) is a 126.745-mile-long (203.976 km) state highway in the U.S. state of South Dakota.
Lewis and Clark Trail 
SD 37 north of Springfield 
US 81 / SD 50 in Yankton 
