17 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Manhattan | 1 | 54,974 | 54,151 | 0.25% | 2,696 | 20 | City |
| Manhattan | 2 | 2,325 | 2,216 | 1.53% | 73 | 32 | Township |
| Ogden | 3 | 2,112 | 2,073 | 1.15% | 171 | 12 | Township |
| Ogden | 4 | 1,650 | 1,668 | -0.18% | 986 | 2 | City |
| Riley | 5 | 961 | 943 | 0.31% | 1,892 | 1 | City |
| Grant | 6 | 924 | 893 | 1.43% | 26 | 36 | Township |
| Wildcat | 7 | 878 | 843 | 1.5% | 30 | 29 | Township |
| Bala | 8 | 716 | 677 | 1.85% | 17 | 42 | Township |
| Sherman | 9 | 601 | 578 | 1.52% | 20 | 29 | Township |
| Leonardville | 10 | 446 | 431 | 0.68% | 1,458 | 0 | City |
| Zeandale | 11 | 350 | 335 | 1.74% | 6 | 60 | Township |
| Jackson | 12 | 301 | 295 | 1.01% | 9 | 32 | Township |
| Swede Creek | 13 | 174 | 169 | 1.16% | 4 | 49 | Township |
| Randolph | 14 | 157 | 159 | 0% | 571 | 0 | City |
| Fancy Creek | 15 | 92 | 90 | 1.1% | 3 | 32 | Township |
| Center | 16 | 78 | 76 | 1.3% | 2 | 32 | Township |
| May Day | 17 | 74 | 70 | 1.37% | 2 | 31 | Township |
Manhattan is the largest city in Riley County, with a population of 54,974.
May Day is the smallest city in Riley County, with a population of 74.
There are 17 cities in Riley County, Kansas.