Onida, SD

Onida is the Sully County seat in central South Dakota, founded on March 28, 1883, by Charles Agar of New York. Agar chose the name from his hometown of Oneida, and the new city quickly gained a courthouse, businesses, and a place on the county’s farm-road map. The 2020 census counted 666 residents. U.S. Highway 83 runs through the area, with the Missouri River and Lake Oahe about 30 miles west.

Sully Buttes High School brings together students from Onida, Agar, and Blunt, and the Chargers give the small county seat a shared school identity. Four churches, a grocery, post office, hardware store, banks, clinic, and car dealerships keep everyday errands close to Main Street. Onida also holds the Sully County Fair and an annual Christmas event with lights, a parade, hay rides, and a craft show. It is a prairie courthouse town surrounded by open farmland, with the county’s outdoor life reaching west toward the Missouri River and Lake Oahe.