South Dakota Highway 1806

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 Mission Ridge Road south of Mission Ridge.

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.

South Dakota Highway 273 (SD 273) is a 12.723-mile-long (20.476 km) north-south state highway in Lyman County, South Dakota. It serves as a southern continuation of SD 1806, connecting it with the town of Kennebec and Interstate 90 (I-90).

SD 273 begins at an interchange with I-90 (Exit 235), with the road continuing south as County Road 19 (CR 19). It heads north to enter the town of Kennebec, passing a couple of businesses as it almost immediately has an intersection with SD 248 (former U.S. Route 16 (US 16)). The highway crosses over a creek before passing along the western edge of downtown. SD 273 passes through some neighborhoods before leaving Kennebec and traveling north through flat farmland for the next several miles. The highway enters the Lower Brule Indian Reservation and comes to an end at the southern terminus of SD 1806 and CR 10. CR 10 leads eastward towards the town of Lower Brule.

The entire length of South Dakota Highway 273 is a rural, two-lane, state highway, located entirely in Lyman County.[4]

SD 273 came about in 1975, when South Dakota renumbered many of its highways.[2]

The entire route is in Lyman County.

Location	mi	km	Destinations	Notes
Kennebec	0.0	0.0	I-90 – Presho, Reliance CR 19 south	Southern terminus; I-90 exit 235; road continues south as CR 19
	0.2	0.32	SD 248 – Presho, Reliance	Former US 16
Lower Brule Indian Reservation	12.723	20.476	SD 1806 north – Fort Pierre CR 10 – Lower Brule	Northern terminus of SD 273, southern terminus of SD 1806
1.000 mi = 1.609 km; 1.000 km = 0.621 mi

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