| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Winnett | 1 | 208 | 187 | 1.46% | 204 | 1 | Town |
Winnett is the largest city in Petroleum County, with a population of 208.
Winnett is the smallest city in Petroleum County, with a population of 208.
There is 1 city in Petroleum County, Montana.