# South Dakota Highway 1806

South Dakota Highway 1806 (SD 1806) is a state highway in the U.S. state of South Dakota. It exists in four distinct sections. Its longest section begins at SD 273 and runs along the Missouri River nearly its whole length, serving Pierre. SD 1806 along with SD 1804 are numbered from the years of the Lewis and Clark Expedition.

## Route description
### Lyman and Stanley Counties

SD 1806 begins at the northern terminus of SD 273 in Lyman County and begins heading northwest. The route remains a two lane road and follows the Missouri River, heading towards Pierre. As it nears Pierre, the route becomes concurrent with US 83 and enters Fort Pierre. At the north end of Fort Pierre, US 83 becomes concurrent with US 14 heading east while SD 1806 splits from US 83 and becomes concurrent with US 14 and SD 34 for nearly a mile, heading west from the Deadwood Street and Yellowstone Street intersection. After one mile of concurrency, SD 1806 splits from US 14/SD 34 and heads north, passing by the Fort Pierre Chouteau National Historic Landmark and remaining parallel with the Missouri River. It then passes by Lake Oahe, intersecting the west end of SD 204 which passes over the Oahe Dam. SD 1806 continues west and remains parallel with the Missouri River until reaching Sansarc Road. The route continues northwest and ends at an intersection with Minneconjou Road south of Mission Ridge.

### Corson County
## History

A portion of SD 1806 near Lake Oahe was numbered as SD 514. It was later redesignated into parts of SD 1804, SD 204, and part of today's portion of SD 1806.

## Major intersections

| County | Location | mi | km | Destinations | Notes |
| Gregory | ​ | 15.68 | 25.23 | US 18 | Southern terminus; road continues unpaved as 361 Avenue |
| Gregory | ​ | 23.86 | 38.40 | Old 1806 Road north | To SD 1806 (Northern Gregory County segment) |
| Gregory | ​ | 25.75 | 41.44 | Mule Head Road | Continuation beyond northern terminus of southern segment |
| Gap in route ||||||
| Gregory | ​ | 37.88 | 60.96 | Old 1806 Road south / Lakeview Drive | Southern terminus of northern segment; road continues east as Lakeview Dr.; Old 1806 Rd. provides access to SD 1806 (Southern Gregory County segment) |
| Gregory | ​ | 48.55 | 78.13 | SD 44 | Northern terminus |
| Gap in route ||||||
| Lyman | Lower Brule Indian Reservation | 138.45 | 222.81 | SD 273 south / Lewis and Clark Trail | Southern terminus; northern terminus of SD 273; road continues east as Medicine Bull Memorial Highway (Iron Nation Road) |
| Stanley | Fort Pierre | 180.05116.94 | 289.76188.20 | US 83 south | Southern end of US 83 concurrency; mileposts change to reflect US 83 mileage |
| Stanley | Fort Pierre | 138.73227.73 | 223.26366.50 | US 14 / SD 34 east / US 83 north / Lewis and Clark Trail – Pierre | Northern end of US 83 concurrency; southern end of US 14/SD 34 concurrency; mileposts change to reflect US 14 mileage |
| Stanley | Fort Pierre | 226.86186.46 | 365.10300.08 | US 14 / SD 34 west – Philip | Northern end of US 14/SD 34 concurrency; mileposts change to reflect SD 1806 mileage |
| Stanley | ​ | 191.60 | 308.35 | SD 204 east to SD 1804 | Western terminus of SD 204 |
| Stanley | ​ | 221.05 | 355.75 | Minneconjou Road | Continuation beyond northern terminus |
| Gap in route ||||||
| Corson | ​ | 359.75 | 578.96 | 280 Avenue | Continuation beyond southern terminus |
| Corson | ​ | 363.43 | 584.88 | US 12 / SD 20 west / Lewis and Clark Trail | Southern end of US 12/SD 20 concurrency |
| Corson | ​ | 364.61 | 586.78 | US 12 / SD 20 east – Mobridge | Northern end of US 12/SD 20 concurrency |
| Corson | ​ | 370.13 | 595.67 | SD 1806 Spur north – Wakpala | Southern terminus of unsigned SD 1806 Spur |
| Corson | Kenel | 386.83 | 622.54 | BIA Rd. 3 / Lewis and Clark Trail | Continuation beyond northern terminus; to ND 1806 |
| 1.000 mi = 1.609 km; 1.000 km = 0.621 mi Concurrency terminus ||||||

## Wakpala spur

South Dakota Highway 1806 Spur (SD 1806P) is a 1.8-mile (2.9 km) long spur route of SD 1806. Although unsigned, it provides access to the town of Wakpala, South Dakota, located in the Standing Rock Indian Reservation.