Sully County, South Dakota Cities (2025)

2 cities

City
Rank
2025 Pop. ↓
2020 Pop.
Annual Change
Density
Area (mi²)
Type
Onida1638667-0.93%9491 City
Agar268650%3320 Town

Sully County Cities Summary

Largest City

Onida is the largest city in Sully County, with a population of 638.

Smallest City

Agar is the smallest city in Sully County, with a population of 68.

10 Largest Cities

There are 2 cities in Sully County, South Dakota.

Location of Sully County