21 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Estelline | 1 | 774 | 744 | 0.78% | 819 | 1 | City |
| Castlewood | 2 | 720 | 700 | 0.56% | 626 | 1 | City |
| Norden | 3 | 705 | 638 | 2.17% | 18 | 39 | Township |
| Lake Norden | 4 | 641 | 560 | 2.56% | 735 | 1 | City |
| Bryant | 5 | 481 | 470 | 0.42% | 918 | 1 | City |
| Hayti | 6 | 447 | 382 | 3% | 1,011 | 0 | Town |
| Bryant | 7 | 345 | 341 | 0.29% | 16 | 21 | Township |
| Estelline | 8 | 338 | 305 | 2.42% | 7 | 47 | Township |
| Oxford | 9 | 331 | 297 | 3.12% | 6 | 52 | Township |
| Cleveland | 10 | 303 | 276 | 1.34% | 9 | 35 | Township |
| Hayti | 11 | 300 | 268 | 2.74% | 9 | 32 | Township |
| Castlewood | 12 | 265 | 238 | 2.32% | 8 | 35 | Township |
| Hamlin | 13 | 265 | 243 | 1.15% | 7 | 36 | Township |
| Dempster | 14 | 247 | 223 | 1.65% | 7 | 36 | Township |
| Opdahl | 15 | 214 | 193 | 1.9% | 6 | 34 | Township |
| Brantford | 16 | 152 | 138 | 2.01% | 3 | 53 | Township |
| Garfield | 17 | 136 | 121 | 3.03% | 4 | 35 | Township |
| Dixon | 18 | 130 | 117 | 3.17% | 4 | 36 | Township |
| Hazel | 19 | 97 | 99 | -1.02% | 401 | 0 | Town |
| Bryant | 20 | 27 | 27 | 0% | 1 | 35 | Township |
| Bryant | 21 | 17 | 17 | 0% | 0.00 | 35 | Township |
Estelline is the largest city in Hamlin County, with a population of 774.
Bryant is the smallest city in Hamlin County, with a population of 17.
There are 21 cities in Hamlin County, South Dakota.