17 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Vermillion | 1 | 12,205 | 11,720 | 0.8% | 2,619 | 4.66 | City |
| Irene | 2 | 440 | 427 | 0.69% | 1,725 | 0.26 | City |
| Vermillion township | 3 | 416 | 380 | 1.96% | 18 | 22.77 | Township |
| Wakonda | 4 | 351 | 348 | 0.29% | 909 | 0.39 | Town |
| Glenwood township | 5 | 233 | 215 | 1.75% | 6 | 35.99 | Township |
| Meckling township | 6 | 227 | 210 | 1.79% | 6 | 36.12 | Township |
| Spirit Mound township | 7 | 226 | 209 | 1.35% | 6 | 36.08 | Township |
| Garfield township | 8 | 208 | 192 | 1.46% | 6 | 35.97 | Township |
| Prairie Center township | 9 | 203 | 185 | 2.01% | 6 | 36.14 | Township |
| Bethel township | 10 | 193 | 183 | 0.52% | 5 | 35.86 | Township |
| Norway township | 11 | 173 | 156 | 2.37% | 7 | 26.14 | Township |
| Pleasant Valley township | 12 | 161 | 152 | 0.63% | 4 | 35.91 | Township |
| Riverside township | 13 | 132 | 120 | 2.33% | 4 | 35.95 | Township |
| Star township | 14 | 130 | 118 | 2.36% | 4 | 35.44 | Township |
| Burbank | 15 | 98 | 112 | 7.69% | 319 | 0.31 | CDP |
| Vermillion township | 16 | 88 | 83 | 2.33% | 2 | 36.03 | Township |
| Meckling | 17 | 46 | 29 | 6.98% | 225 | 0.20 | CDP |
Vermillion is the largest city in Clay County, with a population of 12,205.
Meckling is the smallest city in Clay County.
There are 17 cities in Clay County, South Dakota.