12 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Mount Sterling | 1 | 4,341 | 4,294 | 0.09% | 117 | 37 | Township |
| Mount Sterling | 2 | 2,046 | 2,001 | 0.39% | 1,847 | 1 | City |
| Versailles | 3 | 668 | 654 | 0.15% | 18 | 36 | Township |
| Versailles | 4 | 458 | 446 | 0.44% | 491 | 1 | Village |
| Elkhorn | 5 | 305 | 297 | 0.33% | 8 | 37 | Township |
| Cooperstown | 6 | 274 | 271 | 0% | 7 | 41 | Township |
| Pea Ridge | 7 | 188 | 183 | 0.53% | 5 | 37 | Township |
| Missouri | 8 | 134 | 132 | 0% | 4 | 35 | Township |
| Mound Station | 9 | 120 | 117 | 0.84% | 231 | 1 | Village |
| Buckhorn | 10 | 81 | 80 | 0% | 2 | 38 | Township |
| Ripley | 11 | 69 | 68 | 0% | 11 | 6 | Township |
| Ripley | 12 | 51 | 50 | 0% | 135 | 0 | Village |
Mount Sterling is the largest city in Brown County, with a population of 4,341.
Ripley is the smallest city in Brown County, with a population of 51.
There are 12 cities in Brown County, Illinois.