9 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Clay Center | 1 | 4,004 | 4,202 | -0.82% | 1,255 | 3 | City |
| Wakefield | 2 | 828 | 863 | -0.72% | 1,666 | 0 | City |
| Green | 3 | 224 | 203 | 1.36% | 5 | 48 | Township |
| Morganville | 4 | 180 | 182 | 0% | 531 | 0 | City |
| Green | 5 | 90 | 96 | -1.1% | 462 | 0 | City |
| Longford | 6 | 70 | 73 | 0% | 493 | 0 | City |
| Manchester | 7 | 52 | 49 | 1.96% | 325 | 0 | City |
| Vining | 8 | 38 | 40 | 0% | 178 | 0 | City |
| Oak Hill | 9 | 25 | 24 | 0% | 490 | 0 | City |
Clay Center is the largest city in Clay County, with a population of 4,004.
Oak Hill is the smallest city in Clay County, with a population of 25.
There are 9 cities in Clay County, Kansas.