Dewey County, South Dakota

Dewey County
County
Forest City Bridge
Location within the U.S. state of South Dakota
South Dakota's location within the U.S.
Coordinates: 45°10′N 100°53′W / 45.16°N 100.88°W / 45.16; -100.88
Country	United States
State	South Dakota
Founded	1883 (created) 1910 (organized)
Named for	William P. Dewey
Seat	Timber Lake
Largest community	North Eagle Butte
Area
• Total	2,445 sq mi (6,330 km2)
• Land	2,302 sq mi (5,960 km2)
• Water	143 sq mi (370 km2)  5.8%
Population  (2020)
• Total	5,239
• Estimate  (2023)	5,208
• Density	2.1/sq mi (0.83/km2)
Time zone	UTC−7 (Mountain)
• Summer (DST)	UTC−6 (MDT)
Congressional district	At-large

Dewey County is a county in the U.S. state of South Dakota. As of the 2020 census, the population was 5,239.^[1] Its county seat is Timber Lake.^[2] The county was created in 1883 and organized in 1910.^[3] It was named for William P. Dewey,^[4] Territorial surveyor-general from 1873 to 1877.

Almost the entire county lies in the Cheyenne River Indian Reservation. The balance of the county, along its extreme northern county line, lies in the Standing Rock Indian Reservation. It is one of five South Dakota counties that are contained within Indian reservations.