Buffalo County is a county in South Dakota, United States, on the Missouri River in the central part of the state. It had a population of 1,948 at the 2020 census and covers 471 square miles (1,220 km2) of land plus 16 square miles (41 km2) of water, centred near 44°02′N 99°12′W.
Gann Valley is the county seat, and its postal code is 57341. The county has no incorporated cities or towns — its handful of communities are all unincorporated or census-designated places — and it observes Central time.
Towns & Villages in Buffalo County
Buffalo County has never had an incorporated municipality; every place on the list below is a census-designated place (CDP) or a smaller unincorporated community. Most of the county’s population and land base sit inside the Crow Creek Indian Reservation, home of the Crow Creek Sioux Tribe.
| Place | Type | Pop. | ZIP |
|---|---|---|---|
| Fort Thompson | CDP | — | 57339 |
| Gann Valley | CDP · seat | 10 | 57341 |
| Lees Corner | Unincorp. | — | — |
| Shelby | Unincorp. | — | — |
Fort Thompson, on the Missouri River at the Big Bend Dam, is the county’s largest community by a wide margin. Gann Valley, the seat, is the least populous county seat in the United States — its 2020 census count was just 10 people.
ZIP Codes
- 57341 — Gann Valley (post office town; also serves the surrounding county seat area)
- 57339 — Fort Thompson (also serves the Big Bend Dam area of the reservation)
Lees Corner and Shelby are too small to carry their own ZIP code and are served by the nearest post office town above.
Geography
The Missouri River forms Buffalo County’s western and southwestern boundary, impounded here as Lake Sharpe behind the Big Bend Dam. Crow Creek drains the southern and western part of the county before reaching the river near the county’s southwest corner. The terrain is rolling prairie tableland typical of the Missouri Plateau, with almost the entire county inside the Crow Creek Indian Reservation.
Buffalo County borders Hyde County to the north, Hand County to the northeast, Jerauld County to the east, Brule County to the south, Lyman County to the southwest across the Missouri River, and Hughes County to the west across the Missouri River.
Demographics
The 2020 census counted 1,948 residents, giving the county a density of roughly 4 people per square mile — among the lowest in South Dakota. Fort Thompson is by far the largest community; Gann Valley, the seat, has only 10 residents. A 2013 Census Bureau estimate placed Buffalo County’s median household income at $21,572, among the lowest of any county in the nation at the time, well below the South Dakota median of $71,810. The county’s population is overwhelmingly Native American, reflecting its location almost entirely within the Crow Creek Indian Reservation.
Economy & Local Life
The Crow Creek Sioux Tribal government is the county’s largest employer, alongside the Bureau of Indian Affairs and the Crow Creek Reservation’s schools and health services. The Lode Star Casino & Hotel near Fort Thompson, operated by the tribe, is a major local employer and draws visitors off US Highway 16/281 and SD Highway 47. Ranching and hunting on the reservation’s grasslands, and fishing and recreation on Lake Sharpe below the Big Bend Dam, round out the local economy.
History
Buffalo County was created in 1864, during the Dakota Territory era, and formally organized in 1871; it takes its name from the American bison that once ranged the Missouri Plateau prairie. Fort Thompson began as a fort and Indian agency in the early 1860s, established to relocate Santee Sioux and later becoming the administrative center of the Crow Creek Indian Reservation. In the 1960s, construction of the Big Bend Dam on the Missouri River flooded bottomland along the river and displaced reservation families, a disruption still felt in the community today.
Getting There
US Highway 16/281 and SD Highway 47 are the county’s main routes, with SD Highway 47 crossing the Missouri River at the Big Bend Dam near Fort Thompson.
- Chamberlain, SD — about 30 miles south
- Pierre, SD — about 45 miles northwest
- Huron, SD — about 60 miles northeast
- Mitchell, SD — about 75 miles southeast
The nearest commercial airport is Pierre Regional Airport in Pierre.
Frequently Asked Questions
Where is Buffalo County, South Dakota?
It sits on the Missouri River in central South Dakota, almost entirely within the Crow Creek Indian Reservation.
What is the population of Buffalo County?
1,948 people, per the 2020 census.
How big is Buffalo County?
471 square miles (1,220 km2) of land plus 16 square miles (41 km2) of water.
What is the county seat of Buffalo County?
Gann Valley, which is also the least populous county seat in the United States, with a 2020 population of just 10.
How many towns are in Buffalo County?
None are incorporated; the county’s main communities are Fort Thompson and Gann Valley, both census-designated places, plus the smaller unincorporated places of Lees Corner and Shelby.
What ZIP codes are in Buffalo County?
57341 (Gann Valley) and 57339 (Fort Thompson).
What tribal reservation covers Buffalo County?
The Crow Creek Indian Reservation, home of the Crow Creek Sioux Tribe, covers most of the county’s land base.
More counties in this state: Towns and villages in South Dakota.