Sully County, South Dakota

Sully County
Sully County
County
	Sully Courthouse (2013)
	Location within the U.S. state of South Dakota
	South Dakota's location within the U.S.
	Coordinates: 44°43′N 100°08′W / 44.71°N 100.13°W
Country	United States
State	South Dakota
Founded	1873 (created); 1883 (organized)
Named for	Alfred Sully
Seat	Onida
Largest city	Onida
Area
• Total	1,070 sq mi (2,800 km2)
• Land	1,007 sq mi (2,610 km2)
• Water	63 sq mi (160 km2) 5.9%
Population (2020)
• Total	1,446
• Estimate (2023)	1,494
• Density	1.4/sq mi (0.52/km2)
Time zone	UTC−6 (Central)
• Summer (DST)	UTC−5 (CDT)
Congressional district	At-large
Website	www.sullycounty.net

Sully County is a county in the U.S. state of South Dakota. As of the 2020 census, the population was 1,446,^[1] making it the fifth-least populous county in South Dakota. Its county seat is Onida.^[2] The county was created in 1873 and organized in 1883.^[3] It is named after General Alfred Sully, who built Fort Sully.^[4]

Sully County is included in the Pierre, SD Micropolitan Statistical Area.

^ "State & County QuickFacts". United States Census Bureau. Retrieved March 20, 2024.
^ "Find a County". National Association of Counties. Retrieved June 7, 2011.
^ "Dakota Territory, South Dakota, and North Dakota: Individual County Chronologies". Dakota Territory Atlas of Historical County Boundaries. The Newberry Library. 2006. Archived from the original on April 2, 2018. Retrieved March 31, 2015.
^ Legislative Manual, South Dakota, 2005, p. 597.