Interstate 90 (I-90) in the

US state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its so ...

South Dakota South Dakota (; Sioux language, Sioux: , ) is a U.S. state, state in the West North Central states, North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Dakota people, Dakota Sioux ...

traverses east–west through the southern half of the state.

Route description

I-90 enters South Dakota in Lawrence County as a four-lane divided highway. It enters concurrently with US Highway 14 (US 14) and passes through the town of

Spearfish Spearfish may refer to: Places * Spearfish, South Dakota, United States * North Spearfish, South Dakota, United States * Spearfish Formation, a geologic formation in the United States Biology * ''Tetrapturus'', a genus of marlin with shorter ...

, where it shares another concurrency with US 85 from exit 10 to exit 17. From there it passes several miles north and east of the tourist town of

Deadwood Deadwood may refer to: Places Canada * Deadwood, Alberta * Deadwood, British Columbia * Deadwood River, a tributary of the Dease River in northern British Columbia United States * Deadwood, California (disambiguation), several communit ...

before entering Meade County, going just to the west of Sturgis. Another concurrency is with

South Dakota Highway 34 South Dakota Highway 34 (SD 34) is a state route that runs parallel to Interstate 90 across the entire state of South Dakota. It begins at the Wyoming border west of Belle Fourche, as a continuation of Wyoming Highway 24 (WYO 24). The e ...

(SD 34) from exit 23 at Whitewood to exit 30, the west exit of Sturgis, where there starts a concurrency with SD 79. The freeway generally passes along the north and east edges of the

Black Hills The Black Hills is an isolated mountain range rising from the Great Plains of North America in western South Dakota and extending into Wyoming, United States. Black Elk Peak, which rises to , is the range's highest summit. The name of the range ...

. The route then enters Pennington County, where it passes through the northern edge of

Rapid City Rapid City is the county seat of Pennington County, South Dakota, United States. It is located on the eastern slope of the Black Hills in western South Dakota and was named after Rapid Creek, where the settlement developed. It is the second-mo ...

, gateway to the

and the nearest passing to

Mount Rushmore National Memorial The Mount Rushmore National Memorial is a national memorial centered on a colossal sculpture carved into the granite face of Mount Rushmore (, or Six Grandfathers) in the Black Hills near Keystone, South Dakota, United States. The sculpto ...

, as well as other scenic attractions including

Custer State Park Custer State Park is a South Dakota State Park and wildlife reserve in the Black Hills of the United States. Located in Custer County, the park is South Dakota's first and largest state park, named after Lieutenant Colonel George Armstrong C ...

and the Needles Highway. Rapid City is also where the interstate has its westernmost auxiliary route, I-190, which links the Interstate to the western edge of the downtown area. SD 79's concurrency ends at exit 61 on the east side of the city. From Rapid City, the route heads east, passing between

Box Elder ''Acer negundo'', also known as the box elder, boxelder maple, Manitoba maple or ash-leaved maple, is a species of maple native to North America from Canada to Honduras. It is a fast-growing, short-lived tree with opposite, ash-like compound l ...

to the south and

Ellsworth Air Force Base Ellsworth Air Force Base (AFB) is a United States Air Force (USAF) base located about northeast of Rapid City, South Dakota, just north of the town of Box Elder. The host unit at Ellsworth is the 28th Bomb Wing (28 BW). Assigned to the Glob ...

to the north before heading toward

Wall A wall is a structure and a surface that defines an area; carries a load; provides security, shelter, or soundproofing; or serves a decorative purpose. There are various types of walls, including border barriers between countries, brick wal ...

on to Jackson County. Exits 110 and 131 for

Badlands National Park Badlands National Park () is a List of national parks of the United States, national park of the United States in southwestern South Dakota. The park protects of sharply Erosion, eroded buttes and Pinnacle (geology), pinnacles, along with the l ...

to the south ( SD 240) are within either way of the county line. The concurrency for US 14 ends at exit 112 just east of Wall; here, US 14 runs due east and will connect to the city of

Philip Philip, also Phillip, is a male name derived from the Macedonian Old Koine language, Greek (''Philippos'', lit. "horse-loving" or "fond of horses"), from a compound of (''philos'', "dear", "loved", "loving") and (''hippos'', "horse"). Prominen ...

and the capital city of

Pierre Pierre is a masculine given name. It is a French form of the name Peter. Pierre originally meant "rock" or "stone" in French (derived from the Greek word πέτρος (''petros'') meaning "stone, rock", via Latin "petra"). It is a translation ...

From there, the route passes mostly east–west through Jackson and

Jones Jones or Joneses may refer to: People and fictional characters *Jones (surname), a common Welsh and English surname * List of people with surname Jones, including fictional characters ** Justice Jones (disambiguation) ** Judge Jones (disambiguati ...

counties. There are short concurrencies with SD 73 (from the west entering Kadoka) and SD 63 in Jackson County. I-90 crosses the Central–

Mountain A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited summit area, and is usually higher t ...

timezone boundary on the west edge of Jones County between milemarkers 174 and 175. Then, at Murdo, a concurrency begins with US 83 at exit 192 and continues to exit 212. It is in Lyman County, at exit 212 in Vivian, that the highway provides its closest link to the capital of

, along US 83, some north. The road crosses the

Missouri River The Missouri River is a river in the Central United States, Central and Mountain states, Mountain West regions of the United States. The nation's longest, it rises in the eastern Centennial Mountains of the Bitterroot Range of the Rocky Moun ...

Lake Francis Case Lake Francis Case is a large reservoir impounded by Fort Randall Dam on the Missouri River in south-central South Dakota, United States. The lake has an area of and a maximum depth of . Lake Francis Case has a length of approximately and has a ...

, between the towns of Oacoma and Chamberlain, also crossing into Brule County. I-90 Business (I-90 Bus.) runs from exit 260 at Oacoma to downtown Chamberlain across the Missouri River on the nearby Chamberlain Bridge and returns to I-90 at exit 265. Beginning there is a short concurrency with SD 50 heading to Pukwana, and also in Brule County is another short concurrency with SD 45 starting at Kimball. I-90 then continues through Aurora County (connecting to White Lake and Plankinton), Davison County (where Mt. Vernon, Mitchell, and the Corn Palace are located), Hanson County (

Alexandria Alexandria ( ; ) is the List of cities and towns in Egypt#Largest cities, second largest city in Egypt and the List of coastal settlements of the Mediterranean Sea, largest city on the Mediterranean coast. It lies at the western edge of the Nile ...

), and McCook County ( Salem). Then comes the state's most populous county, Minnehaha. After passing the communities of

Humboldt Humboldt may refer to: People * Alexander von Humboldt, German natural scientist, brother of Wilhelm von Humboldt * Wilhelm von Humboldt, German linguist, philosopher, and diplomat, brother of Alexander von Humboldt Fictional characters * Hu ...

and

Hartford Hartford is the List of capitals in the United States, capital city of the U.S. state of Connecticut. The city, located in Hartford County, Connecticut, Hartford County, had a population of 121,054 as of the 2020 United States census, 2020 ce ...

, the Interstate intersects the only other major Interstate in the state,

I-29 I29 may refer to: * Interstate 29 Interstate 29 (I-29) is an Interstate Highway in the Midwestern United States. I-29 runs from Kansas City, Missouri, at a junction with I-35 and I-70, to the Canada–US border near Pembina, North Dakota ...

, at

Sioux Falls Sioux Falls ( ) is the most populous city in the U.S. state of South Dakota and the 117th-most populous city in the United States. It is the county seat of Minnehaha County and also extends into northern Lincoln County. The population was 192 ...

, the largest city. Just east of I-29 is where I-90 meets the northern terminus of I-229. East of Brandon and northeast of

Valley Springs Valley Springs may refer to some places in the United States: * Valley Springs, Arkansas, located in Boone County * Valley Springs, California, located in Calaveras County * Valley Springs, South Dakota Valley Springs is a city in Minnehaha Cou ...

, it then ends its trip through South Dakota of before entering

Minnesota Minnesota ( ) is a U.S. state, state in the Upper Midwestern region of the United States. It is bordered by the Canadian provinces of Manitoba and Ontario to the north and east and by the U.S. states of Wisconsin to the east, Iowa to the so ...

and Rock County, just west of the towns of Beaver Creek and Manley. Since April 2015, the speed limit is between the Rapid City and the

state line, except for the segment between Veterans Parkway and Marion Road in Sioux Falls, where the speed limit is . The speed limit remains between Rapid City and the

Wyoming Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...

state line.

Codified law

The South Dakota section of I-90 is defined at South Dakota Codified Laws § 31-4-184.

Transit

Jefferson Lines Jefferson Lines (JL or JLI) is a regional intercity bus company operating in 14 states in the Midwest and the West of the United States. History The company is operated by Jefferson Partners L.P., located in Minneapolis, Minnesota. Jefferson P ...

provides intercity bus service along the length of I-90 in South Dakota serving seven communities along the route with major transfer points at the Sioux Falls Bus Station and in Vivian.

History

I-90 was constructed in the 1960s and 1970s. The four-lane Interstate replaced old US 16 as the main road connecting Rapid City and Sioux Falls. Much of Old US 16 remains intact; however, I-90 has absorbed sections and likewise has reshaped the economies of many southern South Dakota towns. Driver-oriented businesses and hotels opened near new exits on I-90, along with roadside attractions to lure in tourists. The final section of I-90 in the state opened in November 1976 between the Wyoming state line and Spearfish. In the city of

, exit 66, which crossed SD 435, was closed on October 1, 2003, after a 10-month delay. The exit was closed and removed as a result of the

South Dakota Department of Transportation The South Dakota Department of Transportation (SDDOT) is a state government organization in charge of maintaining public roadways of the U.S. state of South Dakota. South Dakota has 82,447 miles of highways, roads and streets, as well as 5,905 ...

(SDDOT)'s efforts to move traffic away from a potential crash site at the end of the

Ellsworth AFB Ellsworth Air Force Base (AFB) is a United States Air Force (USAF) base located about northeast of Rapid City, South Dakota, just north of the town of Box Elder. The host unit at Ellsworth is the 28th Bomb Wing (28 BW). Assigned to the Glob ...

runway. The partial cloverleaf interchange of exit 66 was also demolished shortly thereafter. Exit 67, which was constructed not too long before the closure of exit 66, is now used as the main entrance and exit feeder to the base, and it is less likely to be impacted by a potential crash. Local citizens and officials feared the lack of entrances which access the Ellsworth AFB would cause traffic issues and moving businesses from near the old exit would cause some to close and affect tax revenue. Land near exit 66 began to be purchased in 2004, including the former

McDonald's McDonald's Corporation, doing business as McDonald's, is an American Multinational corporation, multinational fast food chain store, chain. As of 2024, it is the second largest by number of locations in the world, behind only the Chinese ch ...

property. On May 24, 2012, the South Dakota Transportation Commission declared the entire length of I-90 as part of the National Purple Heart Trail, naming it the Purple Heart Memorial Highway, named after the military decoration of the same name.

Exit list

References

External links