Dewey County

Dewey County is an administrative division in South Dakota with rolling hills that slope toward the southeast into the Missouri River basin. The Moreau River flows east-northeasterly across the landscape before joining the Missouri River, which forms the county's southeastern boundary.

The county was established in 1883 and named after William P. Dewey, who served as Territorial surveyor-general during the 1870s. This naming honored his contributions to the area's early mapping and territorial development.

The area sits within the Cheyenne River Indian Reservation, where tribal traditions and contemporary Native American life shape the community's character. Local towns and gatherings reflect this connection, which influences how people here live and interact with one another.

Timber Lake serves as the county seat and houses administrative services and government offices for those needing to conduct county business. Government facilities are located in central places that residents and visitors can easily access.

The Moreau River, flowing through the area, takes a distinctive path as it winds toward the Missouri River through changing terrain. This waterway historically shaped how people and resources moved through the region.

Location: South Dakota

Inception: 1883

Capital city: Timber Lake

Shares border with: Corson County, Walworth County, Potter County, Sully County, Stanley County, Ziebach County, Haakon County

GPS coordinates: 45.16000,-100.88000

Latest update: December 8, 2025 13:43