Sully County, organized in 1883, will celebrate 125 years in 2008. Sully County is located in central South Dakota, thirty miles north from South Dakota's State Capital, Pierre. The county is named after General Alfred Sully, who built Fort Sully near the Missouri River.  Sully County has two communities, Agar and Onida. Onida is the County Seat and this is where the courthouse is located.

 

Population (2000 Census): 1,556

Total Area: 1,070 Square Miles