Sully County

Also known as Sully County, South Dakota, Sully County, SD

county in South Dakota, United States

Key facts

Country: United States
State: South Dakota
Founded: 1873 (created), 1883 (organized)
Named after: Alfred Sully
Seat: Onida
Largest city: Onida
Total: 1,070 sq mi (2,800 km )
Land: 1,007 sq mi (2,610 km )
Water: 63 sq mi (160 km ) 5.9%
Estimate 2025: 1,479
Density: 1.436/sq mi (0.5544/km )
Time zone: UTC−6 ( Central )
Summer dst

Article

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

Sully County is included in the Micropolitan Statistical Area of Pierre.