Alignment: SD-258 to 1 mile north of SD-258, just east of Plankinton.

Distance: 1 mile.

History and Notes: SD-203 is an unmarked road, leading to a state training school.

Alignment: SD-1804 to SD-1806 over the Oahe Dam north of Pierre.

Distance: 1 mile.

History and Notes: Formerly part of SD-514.

Attractions Along the Way: Oahe Dam (north of Pierre); Oahe Chapel (north of Pierre).

Alignment: Wyoming border (US-212) northwest of Belle Fourche to Minnesota border (US-212) south of Revillo

Distance: 412 miles.

NHS: Entire route.

Intersecting Interstates: I-29 at Watertown.

Multiplexing: Shared alignment with SD-79 for 3 miles south from Newell; with SD-73 for 3 miles west from Faith; with SD-63 for 3 miles either side of Eagle Butte; with SD-1804 for 4 miles east from the Missouri River; with US-83 for 1 mile, west of Gettysburg; with SD-47 from 1 mile south of Lebanon to 3 miles east of Seneca; with SD-45 from 5 miles east of Faulkton to 8 miles west of Rockham; with US-281 through Redfield; with SD-37 for 5 miles west from Doland; with SD-25 for 1 mile west of Henry; with SD-15 from Tunerville to 3 miles north and 2 miles east of Tunerville.

Spurs and Alternates: Business US-212 along the east side of Belle Fourche.

Multi-lane Segments: SD-139 to I-29.

Lewis and Clark Trail: US-83 to Missouri River

History and Notes: Not part of the 1926 highway plan, but was designated by 1931. Extended along the old SD-22 route.

Attractions Along the Way: Ben Ash Monument (west of Maurine); Pickler Mansion (Faulkton); Faulk County Courthouse (Faulkton); Abbie Gardner Monument (north of Redfield); Fisher Grove State Park (Frankfort); Arthur Mellette House (Watertown).

Follow US-212 across: Montana, Wyoming, and Minnesota

Alignment: Wendt to US-83 near Ft. Pierre.

History and Notes: Decommissioned in 1991.

Alignment: Wyoming line west of Custer to Rapid City

History and Notes: A US route from 1933. This followed the present US-16 from the Wyoming line to Custer, ALT US-16 and SD-36 from Custer to Hermosa, and SD-79 north to Rapid City. The route continued into Wyoming, and existed there from 1930-1934.

Alignment: I-29 at exit 127 to SD-13 west of Elkton.

History and Notes: Old designation of the current SD-324, in effect 1976-1996. Much of this route is on an old US-14 alignment from before 1936.

Alignment: Alpena to SD-37 south of Huron.

Distance: 8 miles.

History and Notes: Designated in 1976, replacing a segment of SD-32.

Alignment: I-29 on south side of Sioux Falls to I-90 on northeast side of Sioux Falls.

Distance: 10 miles.

Intersecting Interstates: I-90 and I-29, both in Sioux Falls.

Business Routes: Loop I-229 in Sioux Falls.

NHS: Entire length.

History and Notes: The 1960 Rand McNally atlas showed I-29 and I-229 in Sioux Falls reversed; I-29 would continue due north from the current I-90/I-229 intersection, running a few miles east of its current alignment. It is unknown if I-229 was ever signed as I-29. This route was completed by 1962, and underwent little change until new exits were added at the north and southwest ends during the 1990's.

Attractions Along the Way: USS South Dakota Memorial, Falls of the Big Sioux River, Old Courthouse Museum, Great Plains Zoo and Delbridge Museum (all in Sioux Falls).

Links: Exit Listings at Highway Heaven, Kurumi's I-229 Page

Alignment: Segment 1: BYPASS US-16 near SD-44 on the east side of Rapid City to I-90 exit 61
Segment 2: I-90/US-14 at exit 63 to Box Elder

Distance: Segment 1: 3 miles. Segment 2: 3 miles.

Multi-Lane Segments: Segment extending from I-90 to Box Elder.

History and Notes: This is an unmarked state route. It follows an old alignment of US-14 and US-16.

Links: Mr. Yamamoto's SD-230 Page

Alignment: SD-79 to SD-44 in Rapid City.

History and Notes: An unmarked state route, decommissioned in 1994.

Alignment: SD-34 west of Madison to Lake Herman State Park

History and Notes: Serves the Lake Herman State Park area west of Madison.

Alignment: BYPASS US-16 on southeast side of Rapid City to SD-44 on the east side of Rapid City.

Distance: 1.3 miles

History and Notes: This is an unmarked state route. It leads to the Western Dakota Technical Institute.

Links: Mr. Yamamoto's SD-238 Page

Alignment: Long Lake to SD-10/SD-45 south of Long Lake.

Distance: 9 miles.

History and Notes: Previously known as SD-101, this designation was implemented by 1976.

Alignment: I-90 at Wall to I-90 northeast of Interior.

Distance: 40 miles.

Intersecting Interstates: I-90 in Wall (twice) and northeast of Interior.

History and Notes: "Badlands Loop". Runs through Badlands National Park (fee to drive on this road).

Former ALT US-16; designation changed around 1980, when US-16 was truncated at Rapid City.

The northwest part of the road loops through Wall, following the Business I-90 alignment, thus intersecting I-90 twice.

Attractions Along the Way: Wall Drug (Wall); Badlands National Park

Alignment: US-16/ US-385 near St. Elmo Peak to ALT US-16 near Keystone

Distance: 11 miles.

History and Notes: SD-244 is also known as the "Norbeck Byway". It is named after former U.S. Sen. Peter Norbeck, who introduced legislation in the 1920's to make Mount Rushmore a national monument.

This road had served as a segment of SD-87 in 1971, and was changed to SD-244 around 1977.

Attractions Along the Way: Mt. Rushmore National Memorial (Keystone); Big Thunder Gold Mine (Keystone); Beautiful Rushmore Cave (Keystone)

Links: Mr. Yamamoto's SD-244 Page

Alignment: SD-34 near Stephan to SD-34 southeast of Ft. Thompson

History and Notes: An old alignment of the SD-34/47 multiplex. The move of the multiplex to the west occurred between 1965 and 1971. This route was replaced in 1985 by a realignment and southward extension of SD-47.

Alignment: SD-10 at Jct. SD-45 to US-12 at Roscoe.

Distance: 23 miles.

History and Notes: Designated around 1976.

Alignment: Kadoka (SD-73) to Reliance (SD-47).

Distance: 100 miles.

Multiplexes: Shared alignment with BUSN I-90 through Kadoka and Murdo.

History and Notes: SD-248 is an unmarked state route, which follows the old US-16 alignment.

Alignment: SD-47 at center of Ft. Thompson to SD-34 east of Ft. Thompson

Distance: Approximately 1 mile

History and Notes: I discovered this in a review of SD state laws regarding each highway. I do not know how long it has been in existance.

Alignment: Gregory (US-18) to Nebraska border north of Mills, NE

Distance: 17 miles

History and Notes: This route was first designated around 1980, and only extended 6 miles south of Gregory. It slowly expanded to the south, and currently extends to the state line.

Links: Mr. Yamamoto's SD-251 Page

Alignment: SD-47 north of Bowdle to US-12 east of Bowdle

Distance: 20 miles

History and Notes: Designated in 1975, replacing SD-102.

Alignment: Plankinton to US-281 east of Plankinton.

Distance: 2 miles.

History and Notes: This is an unmarked state route, following the old US-16 alignment through town. Rural street signs indicate the road is named "Highway 16".

Alignment: Alexandria (I-90) to SD-42 southeast of Bridgewater

Distance: 18 miles.

History and Notes: Formerly a part of US-16, and designated around 1980 when US-16 was rerouted onto I-90.

Links: Mr. Yamamoto's SD-262 Page

Alignment: Brandon to Valley Springs.

History and Notes: Designated around 1980, following a portion of old US-16. It was decommissioned in 1999.

Alignment: North Dakota border north of Artas to US-12 south of Java.

Distance: 37 miles.

History and Notes: Designated around 1975; northern segment (north of SD-10) replaced SD-105.

Alignment: I-90 at Kennebec to SD-1806 west of Lower Brule

Distance: 15 miles.

History and Notes: Designated in 1976.

Distance: 233 miles.

Intersecting Interstates: I-90 at Plankinton.

NHS: Wolsey to North Dakota border.

Multiplexing: Shared alignment with SD-10 for 3 miles, between Frederick and Westport; with US-12 through the west side of Aberdeen; with US-212 through Redfield; with US-14 for 3 miles either side of Wolsey; with SD-44 for 3 miles between Corsica and Armour; with US-18 from 6 miles south of Armour to 15 miles southwest of Pickstown.

Multi-lane Segments: Mellette to 5 miles north of Aberdeen, except for a short stretch just south of Aberdeen. A new bypass is also being built around the west side of Aberdeen.

History and Notes: Historical alignments of US-281:

• 1932: Applied to what was SD-41. Segment between US-14 and the North Dakota line was in the same area as today. The road then went to Huron, and followed current SD-37 to 2 miles north of Tripp, ending at the US-18 junction.
• By 1936: Route south of US-14 rerouted, extending from near Wolsey to Plankinton, then west to 6 miles east of Kimball, then south to the Nebraska border near Fairfax. Crossed the Missouri River near the old town of Wheeler (west of Lake Andes).
• Between 1948 and 1953: With the pending completion of Fort Randall Dam and subsequent creation of Lake Francis Case, the crossing at Wheeler was abandoned. US-281 was rerouted from Plankinton to extend 2 miles east, then went south to Armour on what had been the remaining segment of SD-41. Route continued to SD-50, then multiplexed with US-18 west to Lake Andes, and southwest to cross the Missouri River at the new town of Pickstown. Route crossed into Nebraska near Fairfax, as previously been the case.
• Around 1960: The Nebraska entrance of US-281 was moved about 9 miles east.

US-281 between Aberdeen and US-14 is slowly being increased to 4 lanes, as part of the Eastern Dakota Expressway project.

Attractions Along the Way: Dacotah Prairie Museum (Aberdeen); Abbie Gardner Monument (Redfield); Fort Randall (Pickstown); Fort Randall Dam (Pickstown).

Follow US-281 across: North Dakota, Nebraska, Kansas, Oklahoma, and Texas

Links: Information on unique bridge for US-281 bypass of Aberdeen (from South Dakota DOT)

History and Notes: A review of South Dakota legislative statutes indicates that SD-296 was in northwest Turner County, between the county line and SD-17, but did not give more specifics. In any case, it was decommissioned in 1991.

Alignment: Igloo to SD-471 northeast of Igloo

History and Notes: Decommissioned in 1998.

Alignment: SD-50 northwest of Yankton to SD-52 on the west side of Yankton.

Distance: 4 miles.

Alignment: I-29 at exit 127 to SD-13 west of Elkton.

Distance: 8 miles

History and Notes: Designated in 1997, replacing the SD-218 identifier.

History and Notes: This route was listed among South Dakota legislative statutes, the latest of which only said it was from "US-18 north". In any event, it was decommissioned in 1995.

Alignment: SD-240 to Interior (SD-44).

Distance: 2 miles.

History and Notes: Runs through Badlands National Park. Formerly SD-40A.

Alignment: US-85 at Pluma (Deadwood) to Nebraska border (US-385) south of Oelrichs.

Distance: 125 miles.

Multiplexing: Shared alignment with US-16 from 5 miles northeast of Hill City to Custer; with SD-89 from Custer to Pringle; with US-18 from Hot Springs to Oelrichs.

History and Notes: When roads were named rather than numbered, this road was part of both the "Potash Highway" and the "Black Hills Loop Highway." It was originally numbered as US-85E by 1931. By 1936, the Deadwood to Hot Springs segment became part of ALT US-85. Designation changed to the current US-385 in 1958, and was extended southeast to the Nebraska border, replacing that segment of SD-79.

US-385 south of the US-18/SD-79 junction is part of the future "Heartland Expressway", which will link Denver and Rapid City.

Attractions Along the Way: Homestake Gold Mine (Lead); Crazy Horse Monument (north of Custer); Flintstones Bedrock City (Custer); Custer County 1881 Courthouse (Custer); Wind Cave National Park (north of Hot Springs); Mammoth Site (Hot Springs).

Follow US-385 across: Nebraska, Colorado, Oklahoma, and Texas

Links: Dale Sanderson's END US-385 Page, US-385 Strawberry Hill reconstruction near Deadwood (SD Dept. of Transportation)

Alignment: US-18 in southeast Shannon County south to Nebraska border (NE-27)

Distance: 3 miles

History and Notes: Replaced a SD-75 designation in 1975.

Links: Mr. Yamamoto's SD-391 Page

Alignment: Pine Ridge (US-18) to Nebraska border (NE-87)

Distance: 2 miles.

History and Notes: Designated in 1975.

Links: Mr. Yamamoto's SD-407 Page

History and Notes: This was an unmarked state route, connecting New Underwood to I-90. It was previously numbered as SD-116 between 1965 and 1975. It was decommissioned in 1998.

History and Notes: This interstate doesn't exist in South Dakota currently. A freeway extension of I-129 in Sioux City as essentially a beltway around Sioux City led to discussion that I-429 would eventually start in South Dakota north of North Sioux City, working its way toward the I-129 loop, and that when the two met, the whole route would be called I-129. However, the Iowa DOT has no plans to extend the I-129 designation east from its current terminus at I-29, as Tim Habek reports:

I contacted the Iowa DOT and they said that the new US 75 bypass, which opened last November, is NOT going to be designated as I-129 like many assumed. The district office I emailed in Sioux City admits that pretty much everything is up to Interstate standards on the old US 20 bypass along with the new US 75 bypass, but they also say they have no plans on slapping up shields on the route (in which I don't understand why, unless steel signs are getting a little expensive now days). I-129 still exists in Nebraska and the small appearance it makes in Iowa.

Alignment: Box Elder to I-90 exit 66

History and Notes: An unmarked state route, connecting Box Elder to I-90 near Ellsworth AFB. This route was decommmissioned in 1998.

Alignment: I-90 Exit 61 northeast of Rapid City to SD-44 on the east edge of Rapid City

Distance: 3 miles

History and Notes: This is an unmarked state route, leading to the Western Dakota Technical Institute.

Links: Mr. Yamamoto's SD-437 Page

History and Notes: This route was indicated in a review of South Dakota legislative statutes. It was defined as being from SD-79 to Business I-90, which would put it somewhere in the Rapid City area. It was decommissioned in 1994.

History and Notes: This route was indicated in a review of South Dakota legislative statutes. It was defined as running between SD-44 and SD-79, which would put it in Rapid City. It was decommissioned in 1990.

Alignment: I-90 Exit 55 to SD-44, both on the west side of Rapid City

Distance: 4 miles.

History and Notes: This is an unmarked state route.

Alignment: Edgemont (US-18) to Rumford (SD-71)

Distance: 15 miles.

Unpaved Segments: Provo to Rumford.

History and Notes: Designation changed from SD-52 in 1976.

Links: Mr. Yamamoto's SD-471 Page

Alignment: Bald Mountain Mine (southwest of Lead) to US-85/ALT US-14 southwest of Lead

Distance: 2.5 miles.

Attractions Along the Way: Terry Peak (southwest of Lead); Black Hills Mining Museum (Lead)

Alignment: Fort Pierre to Pierre via Oahe Dam

History and Notes: This was a "U" shaped route dating back to around 1965. In 1976, the east leg was redesignated as a segment of SD-1804, and the west leg as SD-1806. The segment across the Oahe Dam is currently SD-204.

Alignment: BIA-9 near the Ziebach/Dewey County line to the Cheyenne River.

History and Notes: Part of the Bureau of Indian Affairs highway system; runs through the Cheyenne River Indian Reservation.

Alignment: BIA-9 near the BIA-8/BIA-19 junction to the Cheyenne River.

History and Notes: Part of the Bureau of Indian Affairs highway system; runs through the Cheyenne River Indian Reservation.

Alignment: BIA-810 to Lake Oahe

History and Notes: Part of the Bureau of Indian Affairs highway system; runs through the Cheyenne River Indian Reservation.

Alignment: BIA-7 near Twin Buttes to Lake Oahe

History and Notes: Part of the Bureau of Indian Affairs highway system; runs through the Cheyenne River Indian Reservation.

Alignment: Segment 1:North Dakota border (ND-1804) northwest of Pollock to an unnumbered county road southeast of Glenham.
Segment 2: 5 miles north of US-212 to Pierre (US-14/US-83).
Segment 3: SD-44/SD-50 west of Platte to an unnumbered county road east of the Platte Creek Recreation Area.
Segment 4: SD-50 west of Lake Andes to Missouri River.

Multiplexing: (Segment 1) Shared alignment with US-12 and SD-20 for 4 miles east from Mobridge. (Segment 2) Shared alignment with US-212 for 5 miles.

Lewis and Clark Trail: (Segment 1) North Dakota border to Mobridge. (Segment 2) US-212 to Pierre.

History and Notes: The segment from Pierre to the Oahe Dam was designated as SD-514 before being changed in 1976.

State routes 1804 and 1806 run in various segments along the east and west banks of the Missouri River, respectively. They were designated in 1976, and are numbered based on the years of Lewis and Clark's travels through the area. These numbers are also used in North Dakota.

Attractions Along the Way: Oahe Dam (north of Pierre); Oahe Chapel (north of Pierre); State Capitol (Pierre); South Dakota State Museum (Pierre); South Dakota Discover Center and Aquarium (Pierre).

Links: Lewis and Clark Trail information (South Dakota Department of Tourism)

Alignment: Segment 1: Kenel to Sacajawea Monument southwest of Mobridge
Segment 2: Stanely County Road 1102 south of Mission Ridge to SD-273
Segment 3: SD-44 near Snake Creek Rec. Area to unmarked county road 5 miles south
Segment 4: Whitestone Bay Rec. Area to Bonesteel (US-18)

Multiplexing: (Segment 1) Shared alignment with US-12 and SD-20 across the Grand River. (Segment 2) Shared alignment with US-14 and SD-34 through Ft. Pierre.

Lewis and Clark Trail: (Segment 1) Entire route. (Segment 3) Entire route.

History and Notes: State routes 1804 and 1806 run in various segments along the east and west banks of the Missouri River, respectively. They were designated in 1976, and the numbers are based on the years of Lewis and Clark's travels through the area. These numbers are also used in North Dakota.

Attractions Along the Way: Sitting Bull's Grave (southwest of Mobridge); Sacajawea Monument (southwest of Mobridge); Oahe Dam (north of Pierre); Oahe Chapel (north of Pierre); Fort Defiance site (west of Lower Brule).

Links: Lewis and Clark Trail information (South Dakota Department of Tourism)