Fall River County is a county in the U.S. state of South Dakota. As of the 2020 census, the population was 6,973. Its county seat is Hot Springs. The county was founded in 1883. It is named for the Fall River which runs through it.
Geography
Fall River County lies at South Dakota's SW corner. Its south borderline abuts the north borderline of the state of Nebraska, and its west borderline abuts the east borderline of the state of Wyoming. The Fall River County terrain contains a mountainous area in the north-central portion, with rolling hills in the rest of the county. Outside the mountainous area, the county's highest point is its SW corner, at ASL. Of the several peaks in the mountainous area, one in the NE portion of that zone rises to ASL. The terrain slopes to the north and east. Discharging from the Angostura Reservoir, the Cheyenne River flows northeasterly through the upper part of the county, departing the county through its north boundary line into Custer County.
Fall River County has a total area of , of which is land and (0.5%) is water.
Major highways
Adjacent counties
- Custer County – north
- Oglala Lakota County – east
- Dawes County, Nebraska – southeast
- Sioux County, Nebraska – south
- Niobrara County, Wyoming – west
Protected areas
- Angostura Reservoir State Game Production Area
- Angostura State Recreation Area
- Bailey State Lakeside Use Area
- Battle Mountain State Game Production Area
- Black Hills National Forest (partial)
- Buffalo Gap National Grassland (partial)
- Friendshuh State Game Production Area (partial)
- Hill Ranch State Game Production Area
- Oral State Game Production Area
- Romey State Game Production Area
- Scherbarth State Game Production Area
- Sheps Canyon State Lakeside Use Area
- Sheps Canyon State Recreation Area
- Williams Dam State Game Production
Lakes
- Angostura Reservoir
- Coldbrook Lake
- Cottonwood Springs Lake