21 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Estelline | 1 | 782 | 747 | 0.9% | 828 | 0.94 | City |
| Castlewood | 2 | 712 | 697 | 0.42% | 619 | 1.15 | City |
| Norden township | 3 | 686 | 636 | 0.88% | 18 | 38.81 | Township |
| Lake Norden | 4 | 624 | 558 | 2.13% | 716 | 0.87 | City |
| Bryant | 5 | 470 | 469 | 0% | 897 | 0.52 | City |
| Hayti | 6 | 428 | 392 | 1.66% | 968 | 0.44 | Town |
| Bryant township | 7 | 347 | 338 | 0.87% | 16 | 21.37 | Township |
| Estelline township | 8 | 324 | 304 | 0.62% | 7 | 46.51 | Township |
| Oxford township | 9 | 317 | 299 | 0.63% | 6 | 51.83 | Township |
| Cleveland township | 10 | 303 | 275 | 1.68% | 9 | 34.70 | Township |
| Hayti township | 11 | 281 | 254 | 1.44% | 9 | 32.38 | Township |
| Castlewood township | 12 | 265 | 247 | 1.15% | 8 | 34.58 | Township |
| Hamlin township | 13 | 264 | 242 | 1.15% | 7 | 35.91 | Township |
| Dempster township | 14 | 234 | 222 | 0% | 7 | 35.95 | Township |
| Opdahl township | 15 | 212 | 193 | 1.44% | 6 | 33.94 | Township |
| Brantford township | 16 | 149 | 139 | 0.68% | 3 | 53.37 | Township |
| Dixon township | 17 | 139 | 126 | 1.46% | 4 | 35.85 | Township |
| Garfield township | 18 | 122 | 113 | 0.83% | 3 | 35.21 | Township |
| Hazel | 19 | 101 | 103 | 0% | 417 | 0.24 | Town |
| Bryant township | 20 | 24 | 24 | 0% | 1 | 34.91 | Township |
| Bryant township | 21 | 17 | 17 | 0% | 0.00 | 35.26 | Township |
Estelline is the largest city in Hamlin County, with a population of 782.
Bryant township is the smallest city in Hamlin County.
There are 21 cities in Hamlin County, South Dakota.