Sully County, South Dakota Cities (2026)

City
Rank
2026 Pop. ↓
2020 Pop.
Annual Change
Density (/mi²)
Area (mi²)
Type
Onida1635665-0.78%9451 City
Agar272671.41%3510 Town

Sully County Cities Summary

Largest City

Onida is the largest city in Sully County, with a population of 635.

Smallest City

Agar is the smallest city in Sully County, with a population of 72.

10 Largest Cities

There are 2 cities in Sully County, South Dakota.

Location of Sully County