6 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Estelline | 1 | 780 | 744 | 0.78% | 825 | 1 | City |
| Castlewood | 2 | 724 | 700 | 0.56% | 630 | 1 | City |
| Lake Norden | 3 | 657 | 560 | 2.5% | 753 | 1 | City |
| Bryant | 4 | 483 | 470 | 0.42% | 922 | 1 | City |
| Hayti | 5 | 460 | 382 | 2.91% | 1,041 | 0 | Town |
| Hazel | 6 | 97 | 99 | 0% | 401 | 0 | Town |
Estelline is the largest city in Hamlin County, with a population of 780.
Hazel is the smallest city in Hamlin County, with a population of 97.
There are 6 cities in Hamlin County, South Dakota.