Alignment: Long Lake to SD-10 south of Long Lake

History and Notes: Designated around 1960, and changed to SD-239 in 1976.

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

Distance: 3 miles.

History and Notes: Was designated as "SPUR" SD-22 sometime between 1965 and 1971, then renamed in 1976.

Links: Mr. Yamamoto's SD-101 Page

Alignment: SD-47 north of Bowdle to US-12 west of Roscoe.

History and Notes: First designated around 1960, applying to the segment from the McPherson County line near Hosmer to US-12. By 1971, an east-west segment from SD-47 to Hosmer was added. Designation changed to SD-253 in 1976.

Alignment: Selby (US-12) to US-12 south of Java.

History and Notes: Designated around 1960. In 1976, the Selby to Java segment became SD-130, and the US-12 to Java segment became part of SD-271.

Alignment: West of Hudson to SD-46.

History and Notes: Was originally designated as "SPUR" SD-46 sometime between 1965 and 1970, then changed in 1976. Decommissioned in 1994.

Alignment: North Dakota border north of Artis to Java.

History and Notes: Designated around 1965, this route originally existed from SD-10 northward. In 1976, it became part of SD-271.

Alignment: Jefferson to North Sioux City.

History and Notes: Designated around 1980, when US-77 was moved onto the I-29 alignment. Decommissioned in 1998.

Alignment: SD-25 at Claire City to SD-127 at Hammer.

Distance: 4 miles.

History and Notes: Designated in 1976, replacing a segment of SD-15.

Links: Mr. Yamamoto's SD-106 Page

Alignment: Big Stone City (US-12) northwest to Jct. SD-15.

Distance: 12 miles.

History and Notes: Runs along Minnesota border. Was designated as SD-15Y until 1976.

Alignment: I-29 west of Dell Rapids to US-18/SD-44 west of Canton.

Distance: 40 miles.

Intersecting Interstates: I-29 west of Dell Rapids; I-90 and I-229 in Sioux Falls.

Multiplexing: Shared alignment with BUSN I-90 and BUSN I-229 through Sioux Falls.

Multi-lane segments: Length of route through Sioux Falls.

History and Notes: Routing of former US-77 was along this road. Designation of SD-115 may have been based on the original designation of US-77 in this area, which was SD-15. SD-115 was designated around 1980, when US-77 was moved onto I-29.

The POW/MIA Memorial Highway designation was passed by the South Dakota legislature in 2000.

In 2001, SD-115 was realigned in Sioux Falls. The previous alignment extended from I-90 along Cliff Avenue, then curving southwest on North Drive to Minnesota Avenue, where it continued southward. The new alignment removes the North Drive segment, taking SD-115 west on Benson Road to Minnesota Avenue north of the airport terminal, continuing south.

Attractions Along the Way: USS South Dakota Memorial, Washington Pavilion of Arts and Sciences, Falls of the Big Sioux River, Old Courthouse Museum, Great Plains Zoo and Delbridge Museum, Center for Western Studies (all in Sioux Falls); EROS Data Center (east of Baltic).

Alignment: I-90 to New Underwood.

History and Notes: A short spur, numbered from US-16, implemented around 1965. This route was decommissioned around 1975, and for awhile in the 1990's, it was unmarked SD-423. It is currently unnumbered.

Alignment: SD-15 at Wilmot to US-12 near Marvin.

Distance: 11 miles.

History and Notes: Replaced SD-15A in 1976.

Alignment: SD-106 at Hammer to North Dakota border (ND-127) northeast of Rosholt.

Distance: 24 miles.

Intersecting Interstates: I-29 near New Effington.

History and Notes: This route was designated around 1980, on an old alignment of US-81 east from New Effington, after US-81 was moved onto I-29. By 1984, after US-81 south of New Effington was moved to the interstate, SD-127 was extended to Sisseton.

Links: Mr. Yamamoto's SD-127 Page

I contacted the Iowa DOT and they said that the new US 75 bypass, which opened (November 2001), 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: Selby (US-83) to Java (SD-271).

Distance: 7 miles.

History and Notes: Designated in 1976, replacing SD-103.

Alignment: US-12 west of Mina to Brown County border northeast of Mina,

Distance: 3 miles.

History and Notes: Passes through the Mina Lake Recreational Area.

Alignment: SD-37 on south side of Groton, to US-12 on east side of Groton.

Distance: Approximately 1 mile.

History and Notes: Indicated in a review of South Dakota state laws regarding each highway.

Alignment: SD-20 northwest of Watertown to US-212 west of Watertown.

Distance: 7 miles.

History and Notes: Runs along west side of Lake Kampeska. The designation was assigned in 1976; this was previously SD-23.

Links: Mr. Yamamoto's SD-139 Page

Alignment: Akaska to US-83 east of Akaska

Distance: 3 miles.

History and Notes: In the early 1950's, this route was the start of SD-20. It was changed to Spur SD-20 between 1965 and 1970. SD-144 designation implemented in 1976.

Alignment: SD-47 near the White River to Colome (US-18).

History and Notes: An old designation of the current SD-49. Designation was changed in 1976.

Alignment: SD-50 just west of the SD-314 junction to SD-52 near Lewis and Clark Lake.

Distance: 2 miles.

Alignment: Jct. SD-15/ SD-20 northwest of Albee east to Minnesota border north of Nassau, MN.

Distance: 12 miles.

History and Notes: Designated in the late 1970's, replacing SD-20A.

Alignment: US-85 near Two Top Butte to Castle Rock (SD-79).

Distance: 5 miles.

History and Notes: West end is at geographical center of U.S.

Designated in 1975. Road was previously part of a SD-79 alignment.

Alignment: I-90 at Presho to Nebraska border (US-183) at Wewela.

Distance: 76 miles.

Intersecting Interstates: I-90 at Presho.

Multiplexing: Shared alignment with SD-44 from 3 miles east of Witten to Winner; with US-18 from 10 miles west of Winner to Colome.

History and Notes: Highway designated in 1932, but existed further south in 1930. What is currently US-183 in South Dakota had previously been SD-55.

Original routing had US-83 and US-183 positions reversed. The original US-183 started at Vivian, then went west to Murdo. From there, the route went south through Mission to the Nebraska border north of Valentine. By 1950, the route was realigned to extend east from Vivian to Presho, then south through Winner and Colome to the Nebraska border. The Vivian to Presho segment was dropped by 1970.

Follow US-183 across: Nebraska, Kansas, Oklahoma, and Texas

Alignment: I-90 in Rapid City to Main St. (SD-79) in Rapid City.

Distance: 1.2 miles.

Intersecting Interstates: I-90 in Rapid City.

NHS: Entire length.

History and Notes: Open by 1962.

Attractions Along the Way: Dinosaur Park (Rapid City); Museum of Geology (Rapid City).

Links: Exit Listings at Highway Heaven; Kurumi's I-190 Page