Alignment: Rosebud to US-18 west of US-83

History and Notes: Part of the Bureau of Indian Affairs (BIA) highway system; runs through the Rosebud Indian Reservation.

Alignment:
Segment 1: Custer County border southwest of Red Shirt to SD-44 east of Potato Creek
Segment 2: SD-50 southeast of Ft. Thompson to SD-45 south of Gann Valley
Segment 3: SD-63 northeast of Green Grass to jct. BIA-3/BIA-4 east of White Horse

Multiplexing: (Segment 1) Shared alignment with BIA-41 for 1.5 miles in northwest Shannon County; with BIA-27 from Rockyford to Sharps Corner

Unpaved Segments: (Segment 1) BIA-41 to BIA-27

History and Notes: Part of the Bureau of Indian Affairs (BIA) highway system. Segment 1 runs through the Pine Ridge Indian Reservation Segment 2 through the Crow Creek Indian Reservation; and Segment 3 through the Cheyenne River Indian Reservation.

Alignment:
Segment 1: Lake Sharpe north of Lower Brule to SD-47 north of Reliance
Segment 2: US-212 near Ridgeview to BIA-4 near White Horse

Multiplexing: Shared alignment with BIA-10 for 2 miles southeast from Lower Brule (Segment 1)

Lewis and Clark Trail: Lower Brule to SD-47 (Segment 1)

History and Notes: Part of the Bureau of Indian Affairs (BIA) highway system. Segment 1 runs through the Lower Brule Indian Reservation; Segment 2 runs through the Cheyenne River Indian Reservation.

Alignment:
Segment 1: Unmarked county road 12 miles north of Timber Lake to US-12 near the west branch of Lake Oahe
Segment 2: SD-20 east of Trail City to White Horse
Segment 3: Ft. Thompson (SD-47) to SD-50 southeast of Ft. Thompson

Multiplexing: (Segment 1) Shared alignment with SD-63 for 1 mile south of Little Eagle.

Unpaved Segments: (Segment 1) Entire route, except for the first 5 miles and the multiplex with SD-63.

History and Notes: Part of the Bureau of Indian Affairs (BIA) highway system. Segment 1 runs through the Standing Rock Indian Reservation; Segment 2 runs through the Cheyenne River Indian Reservation; and Segment 3 runs through the Crow Creek Indian Reservation.

The segments of BIA-4 from SD-20 to BIA-7 near Promise, and SD-50 to Ft. Thompson, are part of the Native American Scenic Byway, which runs south to Chamberlain and north into North Dakota.

Alignment:
Segment 1: BIA-6 near Cherry Creek to BIA-15 south of Dupree
Segment 2: SD-47 southwest of Ft. Thompson to BIA-3/BIA-10 near Lower Brule

Unpaved Segments: Entire route

History and Notes: Part of the Bureau of Indian Affairs (BIA) highway system; segment 1 runs through the Cheyenne River Indian Reservation, and segment 2 through the Lower Brule Reservation.

Segment 2 is part of the Native American Scenic Byway, which runs south to Chamberlain and north into North Dakota.

Alignment: SD-73 south of Faith to Cherry Creek

Unpaved Segments: Entire route

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

Alignment:
Segment 1: 403rd Ave. in Todd County (southeast of Parmelee) to Rosebud
Segment 2: US-212 west of Marksville to BIA-4 north of Promise

History and Notes: Part of the Bureau of Indian Affairs (BIA) highway system. Alignment 1 runs through the Rosebud Indian Reservation; Alignment 2 runs through the Cheyenne River Indian Reservation.

BIA-7 is part of the Native American Scenic Byway, which runs south to Chamberlain and north into North Dakota.

Alignment: Montana border near Camp Crook to Mobridge

History and Notes: This route was originally designated in the mid 1920's as SD-18. Around 1935, the number was changed to SD-8 designation. then to an extension of SD-20 between 1965 and 1970.

Alignment:
Segment 1: SD-34/SD-73 east of Howes to SD-63 near the Cheyenne River crossing
Segment 2: SD-63 in northeast Ziebach county to BIA-4 southeast of Trail City

Unpaved Segments: Entire route

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

Alignment: Britton to North Dakota border

History and Notes: This route was originally a segment of SD-25. Around 1935, SD-25 was adjusted to extend 6 miles east from Britton, before heading north; the original route north from Britton was designated as SD-9. Around 1950, the route number was dropped. This road is currently an unnumbered county road.

Alignment: SD-63 southwest of Eagle Butte to jct. BIA-8/BIA-19 southeast of Parade

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

Alignment: Pollock (SD-1804) to Minnesota border (MN-27) near Browns Valley, MN

Distance: 193 miles

Intersecting Interstates: I-29 east of Sisseton

Multiplexing: Shared alignment with US-83 from 5 miles north to 5 miles south of Herreid; with SD-47 for 1 mile through Eureka; with SD-45 from the SD-247 junction to Leola; with US-281 for 3 miles near Barnard; with SD-37 for 2 miles northeast of Houghton; with SD-27 for 6 miles eastward from Britton

History and Notes: Formerly the "Glacier Trail", SD-10 started out in 1926 as SD-12. Number changed in 1927, presumably to avoid confusion with nearby US-12.

Segment west of US-83 was added in 1961 or 1962.

Attractions Along the Way: Eureka Pioneer Museum (Eureka); Fort Sisseton State Historical Park (southeast of Britton); Roy Lake State Park (southwest of Lake City); North-South Continental Divide (along Minnesota border east of Sisseton)

Links: Mr. Yamamoto's SD Highway 10 Page

Alignment: Jct. SD-1806/SD-273 to SD-47 south of BIA-3/BIA-5 just south of Lower Brule

Lewis and Clark Trail: Entire length

History and Notes: Part of the Bureau of Indian Affairs (BIA) highway system; runs through the Lower Brule Indian Reservation.

BIA-10 is part of the Native American Scenic Byway, which runs south to Chamberlain and north into North Dakota.

Attractions Along the Way: Fort Defiance (west of Lower Brule)

Alignment:
Segment 1: Minnesota border(MN-269) north of Sherman to SD-48 northwest of Akron, IA
Segment 2: SD-50 west of Richland to Business I-29 at Elk Point (Franklin St.)

Distance: Segment 1: 75 miles. Segment 2: 5 miles.

Intersecting Interstates: I-90 at Brandon

Multiplexing: Shared alignment with SD-42 for 3 miles east from the eastern edge of Sioux Falls; with US-18 for 1 mile west of Canton.

Multi-lane Segments: Brandon

History and Notes: 1926 routing had SD-11 extending north through Sioux Falls and Dell Rapids (along current SD-115), and ending at US-14 near Elkton. Between 1932 and 1935, this was changed to the current alignment between Sioux Falls and the Minnesota border; the segment from Flandreau north became SD-13. Southern segment added between 1962 and 1971.

Alignment on east side of Sioux Falls changed in early 1990's; the segment between US-18 and SD-46 was added later in the 1990's.

Attractions Along the Way: Devil's Gulch (Garretson); Palisades State Park (Garretson); Newton Hills State Park (Fairview)

Links: Mr. Yamamoto's SD Highway 11 Page

Alignment: SD-34/SD-73 near the Ziebach/Meade County line to Cherry Creek

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

Alignment: Mound City to Minnesota border southeast of Sisseton

History and Notes: One of the original highway numbers, SD-12 was previously the "Glacier Trail". Designation changed to SD-10 by 1927, presumably to avoid confusion with nearby US-12.

Alignment: North Dakota border (US-12) northwest of Lemmon to Minnesota border (US-12) at Big Stone City

Distance: 323 miles

Intersecting Interstates: I-29 in Roberts County

Multiplexing: Shared alignment with SD-73 from Lemmon to Thunder Hawk; with SD-65 for 1 mile east of McIntosh; with SD-20 from 5 miles west of Mobridge to 4 miles south of Selby; with SD-1804 from Mobridge to 4 miles east of Mobridge; with US-83 from 3 miles northwest of Selby to 4 miles south of Selby; with SD-47 for 7 miles west from Bowdle; with SD-45 for 5 miles east from Ipswich; with US-281 through the west part of Aberdeen

NHS: Entire route

Multi-lane segments: 1 mile at each US-12/US-83 junction; 1.8 miles through Bowdle; 6 miles west of Aberdeen to Andover, except for a short stretch near the Aberdeen Airport. The entire segment from Aberdeen to I-29 is scheduled to be upgraded to 4 lanes, as part of the "Eastern Dakota Expressway" project.

Lewis and Clark Trail: Mobridge to south jct. US-83

History and Notes: This road was originally called the "Yellowstone Trail". It was conceived by Ipswich businessman J.W. Parmley in 1912, as an initial desire for a good road from Ipswich to Aberdeen. The concept then quickly spread in both directions, and ended up as a national marked route. More information can be found here.

US-12 was approved on November 11, 1926, by the American Association of State Highway Officials (AASHO) with routings from Michigan to Montana. The federal official route log for US-12 defined the South Dakota segment as: "Beginning at the Minnesota-South Dakota State line west of Ortonville via Wilbank (sic), Summit, Aberdeen, Selby, Mobridge, McLaughlin, McIntosh to the South Dakota-North Dakota State line east of Lemmon", which is basically where it runs today.

When US-12 was first marked in 1926, it was initially co-signed as SD-16.

A new 4-lane segment of US-12 opened from Andover to Groton on October 20, 2003, as part of the Eastern Dakota Expressway project. Another segment from Andover to Bristol is ready for paving, to be completed in 2004. Work will also be done in 2004 on a 4-lane stretch from Webster to Rush Lake. The entire 4-lane project (Aberdeen to I-29) is scheduled for completion in 2005.

Attractions Along the Way: Petrified Wood Park and Museum (Lemmon); Sitting Bull's Grave (southwest of Mobridge); Sacajawea Monument (southwest of Mobridge); Bangor Monument (south of Selby); Prayer Rock (Ipswich); Easton's Castle (Aberdeen); Dacotah Prairie Museum (Aberdeen)

Follow US-12 across: Washington, Idaho, Montana, North Dakota, Minnesota, Wisconsin, Illinois, Indiana, and Michigan
Historical routings across: Wyoming

Links: Mr. Yamamoto's SD US-12 Page; The Yellowstone Trail, detailing the establishment of this route across the nation; the Federal Highway Administration's (FHWA) history of US-12.

Alignment: Cherry Creek to SD-63 just north of the Cheyenne River

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

Alignment: Mina to US-12 north of Mina

Distance: 0.6 miles

History and Notes: Most likely an unnumbered route, using Edgar Rd, to link Mina to the state highway network.

Links: Mr. Yamamoto's SD Highway 12P Page

Alignment: SD-34 south of Flandreau to US-14 north of Elkton

Distance: 28 miles

History and Notes: This route was originally a segment of SD-11, but was changed to SD-13 between 1932 and 1935. At that time, it also was extended east from its original north end to Elkton, then north to US-14. This was due to a rerouting of US-14 in the early 1930's.

Links: Mr. Yamamoto's SD Highway 13 Page

Alignment: BIA-11 east of Howes to BIA-6 southeast of Red Scaffold

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

Alignment: Wyoming border (US-14) west of Spearfish to Minnesota border (US-14) near Elkton

Distance: 421 miles

Intersecting Interstates: I-90 (co-signed from Wyoming border to Wall); I-29 at Brookings; I-190 at Rapid City

Spurs and Alternates: Bypass US-14 east of Pierre and also north of Brookings; Business US-14 in Huron (may not be "official")

Freeway: Wyoming border to Wall (co-signed with I-90)

NHS: Pierre to Minnesota border, Wall to Wyoming border

Multiplexing: Shared alignment with I-90 from the Wyoming border to 1 mile east of Wall; with US-85 from Spearfish to 5 miles east of Spearfish; with SD-34 from Whitewood to Sturgis; with SD-79 from Sturgis to Black Hawk; with SD-63 from Midland to 4 miles west of Hayes; with SD-34 from SD-63 to Pierre; with US-83 from Ft. Pierre to 5 miles west of Blunt; with SD-45 through Miller; with US-281 from 3 miles northwest of Wolsey to 3 miles southeast of Wolsey; with US-81 for 4 miles south from Arlington

Multi-lane segments: 10 mile stretch near Huron, as part of the "Eastern Dakota Expressway" project.

Lewis and Clark Trail: Pierre

History and Notes: Originally called the "Black and Yellow Trail". According to information from the Federal Highways Adminstration on their US-14 history page, the naming came from references to the Black Hills and Yellowstone National Park, two destinations of the trail. The originally-approved US-14 on November 11, 1926, was defined in South Dakota as: "Beginning at the Minnesota-South Dakota State line east of Elkton via Brockings (sic), Huron, Miller, Heighmore (sic), Pierre, Midland to a junction with Route No. 16 south of Phillip."

US Highways guru Robert Droz provides the flexible early history of US-14 in western South Dakota:

• Preliminary routing (1925-1926): West end at Jct US 16 in Midland.
• Final routing (1926-1927): Extended west to Philip Jct (south of Philip)
• 1928: Extended west along US 16 and US 85 to the SD-WY border
• 1929: Pulled back to Rapid City.
• 1932: Pulled back to Philip Jct.
• 1934: Extended to Rapid City.
• 1935: Extended to Wyoming line and west to Yellowstone National Park.

The segment from Rapid City to Box Elder was 4-laned by 1953. Part of this was incorporated into I-90.

Dale Sanderson provided information on a "Business Loop 14" in Huron:

Old US 14 through Huron and Morningside is not signed as anything from US 14 itself, but heading westbound on it, I observed two interesting "Business 14" signs - one on each side of the river. They were white on green cutouts.

The segment of US-14 from SD-63 to Ft. Pierre is part of the Native American Scenic Byway, which runs north into North Dakota and south to Chamberlain.

Attractions Along the Way: High Plains Western Heritage Center (Spearfish); Matthews Opera House (Spearfish); Black Hills Passion Play (Spearfish); Sturgis Motorcycle Rally (Sturgis); Black Hills Nat'l Cemetery (Sturgis); Poker Alice House (Sturgis); Fort Meade Cavalry Museum (Sturgis); Sturgis Motorcycle Museum (Sturgis); Petrified Forest (east of Piedmont); Mount Rushmore National Memorial (southwest of Rapid City); The Journey Museum (Rapid City); Reptile Gardens (Rapid City); Museum of Geology (Rapid City); Chapel in the Hills (Rapid City); Air and Space Museum (Ellsworth Air Force Base); Wall Drug (Wall); Fort Pierre (Ft. Pierre); Verendrye Monument (Ft. Pierre); State Capitol (Pierre); South Dakota Discovery Center and Aquarium (Pierre); South Dakota National Guard Museum (Pierre); World War II Memorial (Pierre); Dakotaland Museum (Huron); South Dakota State Fair (Huron); Pyle House (Huron); Little Town on the Prairie (DeSmet); McCrory Gardens (Brookings); South Dakota Agricultural Heritage Museum (Brookings); South Dakota Art Museum (Brookings)

Follow US-14 across: Wyoming, Minnesota, Wisconsin, Illinois

Links:Mr. Yamamoto's SD US-14 Page (includes Bypass US-14 info at Pierre and Brookings)

Alignment: I-90 Exit 13 in Spearfish to SD-34 in Sturgis

Distance: 44 miles

Multiplexing: With US-85 from Cheyenne Crossing to Baltimore St. in Lead; with US-85 from Pine St. in Deadwood to US-85 jct. northeast of Deadwood

History and Notes: Implemented in the late 1940's on an old alignment of SD-24, from Whitewood to US-85. By 1957, it extended west to Spearfish, then south to Cheyenne Crossing (US-85), replacing a segment of SD-89, and looping back to Deadwood and Sturgis along the previous US-14, when US-14 was rerouted northwest from Sturgis along the projected I-90 alignment.

The segment of US-14A from I-90 to US-85 is designated as the Spearfish Canyon Scenic Byway.

Attractions Along the Way: High Plains Western Heritage Center (Spearfish); Matthews Opera House (Spearfish); Black Hills Passion Play (Spearfish); Sturgis Motorcycle Rally (Sturgis); Black Hills Nat'l Cemetery (Sturgis); Poker Alice House (Sturgis); Fort Meade Cavalry Museum (Sturgis); Sturgis Motorcycle Museum (Sturgis); Terry Peak Ski Area (southeast of Savoy); Black Hills Mining Museum (Lead); Homestake Gold Mine site (Lead); Deer Mountain Ski Area (southwest of Lead); Broken Boot Gold Mine (Deadwood); Calamity Jane and Wild Bill Hickok Graves (Deadwood)

Links: Spearfish Canyon Scenic Byway

Alignment: Spearfish, I-90/US-85 intersection to Yankee St.

Distance: 0.9 miles

History and Notes: Not marked, US-14L is a former alignment of US-85 into Spearfish from the north.

Alignment: Segment 1: Jct. US-83/198th St west of Blunt to Jct. US-14/308th Ave. west of Blunt
Segment 2: Jct. US-14/West Park Ave. NW to Lincoln Ave. NW (Huron)

History and Notes: Unmarked routes, former alignments of US-14

Alignment: BIA-5 south of Dupree to BIA-6 northwest of Cherry Creek

History and Notes: Part of the Bureau of Indian Affairs (BIA) highway system; runs through the Cheyenne River Indian Reservation. It is a short connector between BIA-5 and BIA-6.

Alignment: Old US-81 (near I-29 exit 213) to I-29 west of Toronto

Distance: 78 miles

Intersecting Interstates: I-29 west of Wilmot and west of Toronto

Multiplexing: Shared alignment with SD-20 from 8 miles south of Milbank to 4 miles west of Revillo; with US-212 from 3 miles south of the Grant/Deuel County line to 3 miles north of Altamont; with SD-28 from I-29 to 2 miles west of Toronto

History and Notes: Originally, SD-15 ran the entire north-south length of South Dakota. It mostly followed the future US-77, which had been designated by 1931. It then went north from Milbank, then west to Wilmont, and north to Sisseton. SD-15 then went north to Hammer along US-81. From there, it went west to Claire City, then north to meet ND-18. By 1932, the only segment remaining was US-12 to the North Dakota line.

In the early 1950's, changes were made to the southern end. SD-15 was rerouted so the south end was at US-12/77 at Milbank; it then went north to Hartford Beach, then west through Wilmot to US-81, before heading north again; the old alignment from Wilmot to US-12 became SD-15A. In 1976, the west (north) end was truncated to US-81; the segments of SD-15 near the North Dakota border became SD-106 and part of a realigned SD-25. After US-77 was decommissioned in the early 1980's, SD-15 then extended along the former's alignment south from Milbank, to the present end at I-29 west of Toronto.

Attractions Along the Way: Hartford Beach State Park (east of Wilmot)

Links: Mr. Yamamoto's SD-15 Page

Alignment: Wilmot to Marvin

History and Notes: This designation was established in the early 1950's on the old route of SD-15. Designation changed to SD-123 in 1976.

Alignment: US-12 at Big Stone City to SD-15 near Hartford Beach

History and Notes: One of two branches off SD-15, SD-15Y was designated in the early 1960's. It was renumbered as SD-109 in 1976.

Alignment: Lemmon to Ortonville, MN

History and Notes: Part of the "Yellowstone Trail", SD-16 was co-signed as US-12 in 1926. SD-16 designation dropped in 1927.

Alignment: I-90 at northeast edge of Rapid City to Jct. SD-79/BYPASS US-16 at southeast edge of Rapid City

History and Notes: Designated in 1991. Stretch of highway from the old BYPASS US-16 to I-90 was designated as an extention of BYPASS US-16 in 1994, eliminating SD-16B.

Alignment: I-90 near downtown Rapid City to Wyoming border (US-16) southeast of Newcastle, WY

Distance: 74 miles

Intersecting Interstates: I-90 and I-190 in Rapid City

Freeway Segments: Main St. to I-90 in Rapid City (co-sign with I-190)

NHS: Entire route

Multi-lane segments: "Mount Rushmore Road", from south side of Rapid City to Keystone

Spurs and Alternates: Bypass US-16 on southeast side of Rapid City; Business US-16 in Hill City.

Multiplexing: Shared alignment with I-190 in Rapid City, for 2 blocks with SD-44 in Rapid City, and with US-385 from Custer to east of Hill City

History and Notes: Also known as the Custer Battlefield Highway, when designated in November 1926, US-16 went from Wyoming to Minnesota:

• Wyoming to Rapid City, along current I-90/US-14. This was co-signed as SD-24 from the Wyoming border to Sturgis;
• Rapid City to Alexander, parallel to the current I-90;
• Alexander to Valley Springs, along current SD-42. This had been part of SD-40;
• Valley Springs to Minnesota border (formerly SD-263, currently unnumbered).

Routing was changed in 1935, to extend US-16 west from Rapid City; it went to Custer via what is now US-16A; the swap to the current alignment was completed in the mid 1950's. The eastern portion was aligned by 1953 to the (current) SD-42/SD-264 alignment.

The segment east of Sioux Falls was decommissioned in 1979, and the remainder from Sioux Falls to Rapid City decommissioned in 1980. Several unposted highway numbers now make up most of the Rapid City to Plankinton segment (see SD-230, SD-248, and SD-258).

In 1998, when legislation was first introduced in the South Dakota legislature to authorize the US-16 Bypass in Rapid City, it was proposed to extend east to Box Elder, along the old US-14/US-16 alignment. This was modified to the present configuration before the legislation was approved.

The US-16 bypass in Rapid City was relocated in 2006, after completion of the Southeast Connector project. It was rerouted east from its previous intersection with SD-79 south of Minnesota St (as was SD-79 itself), then came north to meet I-90 at Exit 61, a little over a mile east of its previous intersection.

Attractions Along the Way: The Journey (Rapid City); Museum of Geology (Rapid City); Black Hills Caverns (Rapid City); Bear Country USA (southwest of Rapid City); Black Hills Reptile Gardens (southwest of Rapid City); Mount Rushmore National Memorial (Keystone, via ALT-16); Beautiful Rushmore Cave (Keystone, via ALT-16); Borglum Historical Center (Keystone, via ALT-16); Harney Peak, highest point in South Dakota (south of Hill City); 1880 Train (Hill City); Crazy Horse Monument (north of Custer); Jewel Cave National Monument (west of Custer); Four Mile Old West Town (west of Custer); National Museum of Woodcarving (west of Custer); Custer County 1881 Courthouse (Custer); Flintstones Bedrock City (Custer)

Follow US-16 across: Wyoming
Historical routings across: Minnesota, Wisconsin, and Michigan

Links: Mr. Yamamoto's South Dakota US-16 Page, Dale Sanderson's END US-16 Page

Alignment: Wall to US-16 west of Kadoka

History and Notes: This route through the Badlands was originally part of SD-40. The US-16A alignment was applied between 1944 and 1948. By 1962, the east end was truncated to Cactus Flats, at the eastern extent of I-90 construction in the area (exit 131). In 1980, the route was redesignated as SD-240 after mainline US-16 was decommissioned east of Rapid City.

Alignment: Custer (US-16/US-385), east then north, to US-16 north of Keystone

Distance: 39 miles

History and Notes: Designated between 1944 and 1948, along what is now the concurrent US-385 alignment; US-16 at the time went south through Keystone, then west along SD-36 to Custer before continuing west to Wyoming. Between 1953 and 1957, US-16 was rerouted onto what had been the alternate route, and the segment of mainline US-16 from Keystone to Custer via SD-36 became the new alternate. This configuration remains in place today.

US-16A from near Custer (SD-89) to near Keystone (SD-244) is part of 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.

Attractions Along the Way: Mount Rushmore National Memorial (Keystone); Big Thunder Gold Mine (Keystone); Beautiful Rushmore Cave (Keystone); Custer State Park (east of Custer); Gordon Stockade (east of Custer); Cosmos of the Black Hills (north of Keystone)

Links: Peter Norbeck Scenic Byway

Alignment: Peever to Milbank

History and Notes: Original 1926 routing. Was renumbered as part of SD-15 in 1927. After a rerouting of SD-15 in the early 1950's, the segment of this road between Wilmot and US-12 became SD-15A, then was changed to SD-123 in 1976. The Peever to Wilmot segment has been unnumbered since.

Alignment: SD-42 west of Sioux Falls to SD-44 at Lennox

Distance: 14 miles

History and Notes: Designation in place by 1929. The original alignment continued south to what is now SD-46 near Centerville; this segment (south of SD-44) was decommissioned in the 1990's.

Attractions Along the Way: Wild Water West Waterpark (west of Sioux Falls)

Links: Mr. Yamamoto's SD-17 Page

Alignment: Montana border near Camp Crook to Mobridge

History and Notes: Original designation from 1926. Changed to SD-8 by 1935, then to SD-20 between 1965 and 1970.

Alignment: Wyoming border (US-18) west of Edgemont to Iowa border (US-18) at Canton

Distance: 448 miles

Intersecting Interstates: I-29 (co-signed for 3 miles) west of Canton

NHS: Wyoming border to Pickstown

Freeway: 3-mile segment west of Canton (co-signed with I-29)

Multi-lane Segments: Hot Springs to Jct. US-385

Spurs and Alternates: BYPASS US-18 along the south side of Hot Springs

Multiplexing: Shared alignment with US-385 from Hot Springs to Oelrichs; with SD-73 from Martin to 5 miles south of Patricia; with US-83 for 3 miles west from Mission; with SD-44 from Jordan Junction to Winner; with US-183 from Jordan Junction to Colome; with SD-47 from Gregory to Burke; with US-281 from near the Nebraska border to 6 miles south of Armour; with SD-50 from Lake Andes to 4 miles east of Ravinia; with SD-19 for 1 mile between Hurley and Viborg; with I-29 for 3 miles southwest of Worthing; with SD-11 for 1 mile west of Canton

Lewis and Clark Trail: Gregory to Pickstown

History and Notes: Designated in 1926, largely replacing SD-50 west of the Missouri River. The official routing was as follows: "Beginning at the Iowa-South Dakota State line west of Beloit via Canton, Parker, Olivet, Burke, Winner, Rosebud, Martin, Ogalla, Hot Springs to the South Dakota-Wyoming State line west of Edgemont."

This road used many names over the early years, including Grant Highway from Hot Springs to Rosebud; Black Hills Sioux Trail from Hot Springs to Winner; Black Hills, Rosebud and Omaha Scenic Highway from Rosebud to Fairfax; and Custer Battlefield Highway between SD-15 (current SD-115) and Canton.

Minor realignments have been made over the years. This includes the segment southeast of Hot Springs (road straightened out); the segment from Pine Ridge to Batesland (segment going north to Wounded Knee was bypassed to the south); Parmlee to Mission (new alignment to bypass Rosebud); Bonesteel to near Armour (original alignment was flooded by the creation of Lake Francis Case).

In this flooded segment, the original US-18 curved northeast from Bonesteel, along Gregory CR 61. At the old town of Wheeler, it headed roughly to Lake Andes. The current alignment in this area is due east from Fairfax (along old SD-54), then northeast through Pickstown (created after the lake was formed in the 1950's), then north to Lake Andes. The old bridge at Wheeler was moved north to Chamberlain, to serve as an additional pair of lanes for US-16.

The segment of US-18 that is multiplexed with US-385 (Oelrichs to east of Hot Springs) is part of the future "Heartland Expressway", which will link Denver and Rapid City. Two additional lanes will be added to this segment; construction is scheduled to begin in 2008.

US-18 from the Wyoming border to Pickstown is part of the Oyate Trail, which continues east to I-29 east of Vermillion.

Attractions Along the Way: Mammoth Site (Hot Springs); Cold Brook Dam (Hot Springs); Wounded Knee Battle Site (northeast of Pine Ridge); Fort Randall Dam (Pickstown); Fort Randall (southwest of Pickstown); Heritage House Museum (Canton)

Follow this road across: Wyoming, Iowa, and Wisconsin

Links: Mr. Yamamoto's US-18 Page, Heartland Expressway page, AARoads Corridor 14 (Heartland Expressway) Information

Alignment: "A" St. and 2nd Ave. in Edgemont

Distance: 0.8 miles

Multiplexes: Shared alignment with SD-471 from US-18 to 2nd Ave.

History and Notes: An unmarked road, maintained by SDDOT, probably on an old alignment of US-18 through town.

Alignment: SD-34 southeast of Madison to Nebraska border (NE-15)

Distance: 100 miles

Intersecting Interstates: I-90 near Humboldt

Multi-lane Segments: First 2 miles southeast of Madison

Multiplexing: Shared alignment with SD-38 for 1 mile west from Humboldt; with SD-42 from Union Center to Pumpkin Center; with SD-44 for 3 miles southeast from Parker; with US-18 for 1 mile between Hurley and Viborg; with SD-46 from 4 miles east of Irene to 2 miles south of Centerville

History and Notes: Unchanged from original 1926 routing, with two exceptions. SD-19 previously went into Centerville along the current SD-19A; this was changed around 1950. In November 2001, SD-19 was extended south from Vermilion, when a new bridge to Nebraska was opened.

Attractions Along the Way: Spirit Mound (north of Vermillion); National Music Museum, W.H. Over State Museum, and Austin-Whittemore House (all in Vermillion)

Links: Mr. Yamamoto's SD-19 Page

Alignment: US-212 between Parade and Ridgeview to jct. BIA-8/BIA-9 southeast of Parade

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

Alignment: SD-19, 6 miles west of Centerville, to SD-19/SD-46, 2 miles south of Centerville

Distance: 8 miles

History and Notes: One of the few remaining "suffixed" state routes. This was originally part of mainline SD-19, but was changed when SD-19 was rerouted west and south of Centerville around 1950.

Links: Mr. Yamamoto's SD-19A Page

Alignment:
Segment 1: Montana border west of Camp Crook to Watertown (US-212)
Segment 2: Old US-81 (2 miles west of I-29 exit 193) to Minnesota border (MN-40) east of Revillo

Distance: Segment 1: 393 miles. Segment 2: 39 miles.

Intersecting Interstates: I-29 near South Shore

Multiplexing: Shared alignment with US-85 for 2 miles south from Buffalo; with SD-79 for 5 miles east from Reva; with SD-73 from Meadow Corner to 3 miles west of Coal Springs; with SD-65 from 1 mile west of the Dewey/Ziebach County line to Isabel; with SD-63 from 7 miles west of Timber Lake to 4 miles west of Trail City; with US-12 from 5 miles northwest of Mobridge to 4 miles south of Selby; with US-83 from 4 miles northwest of Selby to the Walworth/Potter County line; with SD-47 from 1 mile west of Hoven to 3 miles south of Hoven; with SD-45 for 2 miles west of Cresbard; with SD-37 for 3 miles south from Conde; with SD-15 from 8 miles south of Milbank to 3 miles west of Revillo

Multi-lane Segments: Lake Kampeska to Watertown

Unpaved Segments: Montana border to Camp Crook

Lewis and Clark Trail: Mobridge to Walworth/Potter County line

History and Notes: Alignment history:

• Between 1929 and 1932: First designated, extended from SD-45 northeast of Faulkton to Watertown.
• Mid 1940's: Extended west to US-83 at the Walworth/Potter county line.
• By 1953: A short stub was added between US-83 and Akaska, and also on the east end between US-81 and US-77 northeast of Watertown (presumably SD-20 was co-signed with US-81).
• 1954: Extended further east, between US-77 and the Minnesota line, passing just south of Revillo.
• Late 1960's: Stub of SD-20 between Akaska and US-83 redesignated as Spur SD-20; mainline SD-20 was extended north along US-83 to US-12, then through Mobridge, and then westward over what had been SD-8 (old SD-18 from 1926 to about 1935).

The segment between Watertown and I-29 is currently not marked.

The segment of SD-20 from BIA-4 to the Grand River (just west of Mobridge) is part of the Native American Scenic Byway, which runs south to Chamberlain and north into North Dakota.

Attractions Along the Way: 1876 Slim Buttes Battle Sites (Reva); Sitting Bull's Grave (southwest of Mobridge); Sacajawea Monument (southwest of Mobridge); Bangor Monument (south of Selby); Cathedral on the Prairie (Hoven); Redlin Art Center (Watertown); Arthur Mellette House (Watertown)

Links: Mr. Yamamoto's SD-20 Page

Alignment 1: SD-15 (old US-77) west of Revillo to Minnesota border east of Revillo
Alignment 2: SD-20/US-77 (present SD-15) junction east to Minnesota border

History and Notes: Designated around 1970, SD-20A initially used the present SD-20 alignment through Revillo. This was moved to the current SD-158 alignment a few years later. Eliminated in the late 1970's, and later designated SD-158.

Alignment: Akaska to US-83/SD-20 junction east of Akaska

History and Notes: In the early 1950's, this was the start of mainline SD-20. It was changed to SPUR SD-20 between 1965 and 1970. This spur was renumbered as SD-144 in 1976.

Distance: 0.2 mile

History and Notes: A short connector between SD-20 and SD-139 for traffic along the west part of the lake. SD-139 and SD-20 run east-west and parallel each other for about 2/3 mile before SD-139 ends at 451st Ave.

Alignment: Lake Norden (SD-28) to US-81/SD-28 east of Hayti

Distance: 9.5 miles

History and Notes: 1926 alignment had SD-21 co-signed with the newly-assigned US-81 the entire length of South Dakota. Only the current alignment was left by 1935.

Attractions Along the Way: South Dakota Amateur Baseball Hall of Fame (Lake Norden)

Links: Mr. Yamamoto's SD-21 Page

Alignment: Walker (US-12) to SD-63 south of McLaughlin

Unpaved Segments: Bullhead to SD-63

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

Alignment: Hazel to Minnesota border (MN-68) west of Canby, MN

Distance: 53 miles

Intersecting Interstates: I-29 west of Clear Lake

Multiplexing: Shared alignment with US-81 for 2 miles west of Castlewood

History and Notes: The original SD-22, from the 1920's, extended west all the way to the Wyoming border, following what is now US-212. When US-212 was implemented in 1927, SD-22 was placed on a new alignment from SD-45 near Howell (northern Hand County) to SD-41 (current US-281) south of Redfield, on what is now SD-26. The present alignment was in place by 1936, and included a north-south segment from Hazel to US-212. This segment was eliminated in the 1990's.

Links: Mr. Yamamoto's SD-22 Page

Alignment: Along Minnesota border from Gary south to SD-22.

History and Notes: Designated between 1965 and 1971, this route was changed to SD-101 in 1976.

Alignment: Claire City to US-212 west of Watertown

History and Notes: Original 1926 route. By 1936, the only part left was along the west shore of Lake Kampeska. SD-25 was later realigned along much of the old route. The remaining SD-23 segment was redesignated as SD-139 in 1976.

Alignment: Current Jct. SD-20 near Meadow to Wyoming border west of Belle Fourche

History and Notes: Designation from 1926 followed path of current SD-73 southward to Howes, then west along current SD-34 to Sturgis, and followed US-16 (later US-14) to Whitewood. By 1936, the north-south segment was made part of SD-73. Between 1944 and 1948, SD-24 was extended northwest from Whitewood to Belle Fourche, and by 1953, the road extended west from Belle Fourche to the Wyoming line. The route was redesignated as part of SD-34 by 1960.

Alignment: Belle Fourche to Whitewood (west of Sturgis)

History and Notes: Designated around 1940, and decommissioned by 1950 as mainline SD-24 was rerouted onto this alignment. By 1960, it was made part of SD-34.

Alignment:
North segment: North Dakota border (ND-18) north of Claire City to SD-42 south of Emery
South segment: US-18 west of Olivet to SD-50 northwest of Tabor

Distance: North segment: 185 miles. South segment: 22 miles.

Intersecting Interstates: I-90 south of Farmer

Multiplexing: (Segment 1) Shared alignment with SD-10 for 1 mile east from Lake City; with US-212 for 1 mile west of Henry; with SD-28 for 3 miles just north of the Clark/Kingsbury County line; with SD-34 from 1 mile west of Howard to 1 mile east of Roswell; with SD-262 for about 2.5 miles northwest from Emery.

History and Notes: Original 1926 alignment had the south end of SD-25 ending at Howard. From current SD-262, the SD-25 designation was applied northward as construction of the road occurred; the north part of this segment was at Farmer by 1971, Epiphany by 1977, and SD-34 by 1981.

Originally, SD-25 went through Howard, but was shifted west 1 mile in the early 1950's. The Miner County (SD) Pioneer newspaper on July 25, 2002 included a clip from the newspaper in summer 1952 about the subject:

A large crowd was on hand at the courthouse in Howard when the State Highway Commission held the hearing on the moving of Highway 25 to one mile west of Howard. After discussions pro and con, Mrs. Theo Sandler asked that a vote be taken of those present. In the voting, 53 voted against the proposed change and 12 voted for the change. About 20 percent did not vote.

On the north end, SD-25 took a zig-zag route north from De Smet; in 1927, it went through Clark to Webster, then west about 15 miles before heading north to Britton and the North Dakota line northeast of Kidder. In the mid 1950's, the route was realigned so it went straight north from De Smet to US-212 9 miles east of Clark, then after a 1 mile jog east, north to Webster, before resuming the previous alignment to North Dakota. In 1976, SD-25 was shifted east to use old SD-23 from Webster to Lake City; it then curved northeast through Veblin and north again at Hammer (on former SD-15).

The current southern segment was the former SD-35, and was renumbered to SD-25 in 1976.

Attractions Along the Way: Little Town on the Prairie (DeSmet)

Links: Mr. Yamamoto's SD-25 Page

Alignment: SD-25 west of Bryant to SD-15 (US-77) east of Estelline

History and Notes: Designated in the late 1920's. Between 1932 and 1935, this was redesignated as SD-28, when the SD-26 designation was moved further northwest.

Alignment: SD-47 north of Highmore to US-281 south of Redfield

Distance: 50 miles

Multiplexing: Shared alignment with SD-45 for 1 mile east of Polo

History and Notes: Designated around 1935, replacing SD-22.

An extension of SD-26 from Oneida (US-83) to US-281 was planned in the late 1970's; although a road is there, it does not carry the SD-26 designator.

Segment between SD-45 and SD-47 was added between 1957 and 1962.

Links: Mr. Yamamoto's SD-26 Page

Alignment: Olivet to near Tabor

History and Notes: Original 1926 alignment in southern South Dakota. Was made part of SD-35 by 1936. Currently is the southern segment of SD-25.

Alignment: North Dakota border (ND-32) near Havana, ND, to US-12 southeast of Andover, SD

Distance: 52 miles

Multiplexing: Shared alignment with SD-10 for 6 miles east from Britton

History and Notes: Designated in 1976. Was previously the original northern end of SD-25.

Links: Mr. Yamamoto's SD-27 Page

Alignment: Pennington County border south of Scenic to US-18 south of Wounded Knee

Multiplexing: Shared alignment with BIA-2 from Rockyford to Sharps Corner

History and Notes: Part of the Bureau of Indian Affairs (BIA) highway system; runs through the Pine Ridge Indian Reservation.

Attractions Along the Way: Wounded Knee Battle Site (northeast of Pine Ridge)

Alignment: US-281 north of Bonilla to Minnesota border (MN-271) east of Astoria

Distance: 109 miles

Intersecting Interstates: I-29 west of Toronto

Multiplexing: Shared alignment with SD-25 for 3 miles between Willow Lake and Bryant; with US-81 for 1 mile north from Alsville; with SD-15 from I-29 to 2 miles west of Toronto

History and Notes: When designated between 1932 and 1935, it absorbed the old SD-26 and extended from SD-25 west of Bryant to US-77 east of Estelline. An extension westward was made in the mid 1950's. A further extension west to SD-45 may have been marked briefly, but was not indicated as such by 1970. The eastward extension to the Minnesota border occurred between 1948 and 1953.

Attractions Along the Way: South Dakota Amateur Baseball Hall of Fame (Lake Norden)

Alignment: Manderson (BIA-33) to Wounded Knee (BIA-27)

History and Notes: Part of the Bureau of Indian Affairs (BIA) highway system; runs through the Pine Ridge Indian Reservation.

Attractions Along the Way: Wounded Knee National Historic Site (Wounded Knee)

Alignment: North Dakota border (I-29) north of Victor to Iowa border (I-29) at North Sioux City

Distance: 252.5 miles

Intersecting Interstates: I-90 and I-229, both in Sioux Falls

NHS: Entire length

Multiplexing: Shared alignment with US-81 from the North Dakota border to Watertown; with US-18 for 3 miles southwest of Worthing

History and Notes: When the Interstate system was being planned in the 1950's, I-29 was only planned to run from Sioux Falls southward. When the extension northward was proposed, it was originally to run in Minnesota, but was shifted westward due to efforts by Sen. Francis Case. In addition, early planning of this segment of I-29 had the route passing just east of Kranzburg, or about 9 miles east of Watertown. A past president of the Watertown Chamber of Commerce contaced C.L. Chase, a member of the Democratic National Committee, in an effort to get I-29 routed closer to Watertown. The effort was successful; the westward alignment became known locally as the Chase Bend.

Historical construction of I-29:

• Late 1950's: The first segment of I-29 to be completed was in Sioux Falls, from SD-38 to Russell St.
  
• 1961: Segments from Sioux City to SD-50, and southern US-18 junction to I-90, complete by the end of November.
  
• 1962: Northbound bridge over the Big Sioux River at the Iowa border collapsed on April 1, due to flooding.
• 1969: Completed from SD-34 to the Iowa border.
  
• 1971: Additional segment from Brookings to SD-34 complete. Alignment still proposed northward to North Dakota.
  
• 1980: Segment from Peever to Victor under construction; remainder was completed.
  
• 1983: Entire route complete, with the opening of the 10 mile segment from Sisseton to Peever.
  

Reconstruction of I-29 through Sioux Falls, from Madison St. to I-90, was completed late in 2003. This involved making this segment 6 lanes, building an interchange at Benson Rd., reconstructing the Russell St. interchange to remove the southbound left exit and changes to Russell St. itself, and reconstruction of the SD-38 interchange.

Attractions Along the Way: Redlin Art Center (Watertown); Arthur Mellette House (Watertown); McCrory Gardens (Brookings); South Dakota Art Museum (Brookings); South Dakota Agricultural Heritage Museum (Brookings); Great Plains Zoo and Delbridge Museum (Sioux Falls); Washington Pavilion of Arts and Sciences (Sioux Falls); USS South Dakota Memorial (Sioux Falls); Center for Western Studies (Sioux Falls); Sioux Empire Medical Museum (Sioux Falls); Old Courthouse Museum (Sioux Falls); Union Grove State Park (south of Beresford)

Follow I-29 across: North Dakota, Iowa, and Missouri

Links: AARoads I-29 Guide

Alignment:
Segment 1 -- I-29 exit 18 northwest of Elk Point to I-29 exit 15 southeast of Elk Point
Segment 2 -- I-29 exit 132 (US-14) to I-29 exit 133 (Bypass US-14) in Brookings

Multiplexing: (Segment 2) With US-14 and Bypass US-14 in Brookings

History and Notes: Segment 1 designated in 1984. Segment 2 designated sometime after the early 1990's.

Links: Interstate Guide's Business I-29 Page and Business Interstate Highways Photo Page

Alignment: I-29 exit 79 (12th St) in Sioux Falls to SD-115 (Minnesota Ave.) in Sioux Falls

Multiplexing: Shared alignment with SD-42 for entire length

History and Notes: Shield markers for this route in Sioux Falls use the word "Downtown" instead of "Business". The east end of the route is at a junction with Spur I-90 and Loop I-229.

Links: Interstate Guide's Business I-29 Page and Business Interstate Highways Photo Page

Alignment: I-29 exit 2 to Military Road in North Sioux City

History and Notes: An unmarked spur along the former south end of SD-105.

Alignment: Wyoming border southwest of Lead to Minnesota border near Elkton

History and Notes: Original 1926 route. Segment from Wyoming border to Sturgis was a co-sign of US-85; Sturgis to Midland segment was a co-sign of SD-65; Segment from Hayes to Elkton was a co-sign of US-14. Entire route was eliminated by 1930.

Alignment: I-29 at exit 140 (west of White) to Minnesota border (MN-19)

Distance: 17 miles

Intersecting Interstates: I-29 west of White

History and Notes: Designated in the mid 1950's, consisting of two segments -- SD-25 north of De Smet to US-81 south of Lake Poinsett, and also from US-77 west of White to the Minnesota border. These segments were connected by 1960. The segment west of US-77 (I-29) was removed by 1965.