11 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Aberdeen | 1 | 27,660 | 28,437 | -0.46% | 1,675 | 17 | City |
| Groton | 2 | 1,324 | 1,381 | -0.68% | 756 | 2 | City |
| Warner | 3 | 438 | 473 | -1.35% | 1,570 | 0 | Town |
| Frederick | 4 | 206 | 214 | -0.48% | 152 | 1 | Town |
| Hecla | 5 | 180 | 194 | -1.1% | 523 | 0 | City |
| Columbia | 6 | 156 | 159 | 0% | 103 | 2 | City |
| Claremont | 7 | 104 | 109 | -0.95% | 414 | 0 | Town |
| Westport | 8 | 81 | 87 | -1.22% | 345 | 0 | Town |
| Stratford | 9 | 58 | 60 | 0% | 232 | 0 | Town |
| Wetonka | 10 | 12 | 14 | 0% | 49 | 0 | Town |
| Verdon | 11 | 6 | 6 | 0% | 24 | 0 | Town |
Aberdeen is the largest city in Brown County, with a population of 27,660.
Verdon is the smallest city in Brown County, with a population of 6.
There are 11 cities in Brown County, South Dakota.