| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Webster | 1 | 1,638 | 1,721 | -0.85% | 1,010 | 2 | City |
| Waubay | 2 | 474 | 474 | 0% | 326 | 1 | City |
| Bristol | 3 | 270 | 285 | -0.74% | 517 | 1 | City |
| Roslyn | 4 | 178 | 183 | -0.56% | 817 | 0 | Town |
| Pierpont | 5 | 118 | 126 | -0.84% | 776 | 0 | Town |
| Andover | 6 | 68 | 67 | 0% | 252 | 0 | Town |
| Grenville | 7 | 45 | 44 | 0% | 190 | 0 | Town |
| Butler | 8 | 6 | 6 | 0% | 21 | 0 | Town |
Webster is the largest city in Day County, with a population of 1,638.
Butler is the smallest city in Day County, with a population of 6.
There are 8 cities in Day County, South Dakota.