| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Manhattan | 1 | 54,699 | 54,154 | 0.05% | 2,683 | 20 | City |
| Ogden | 2 | 1,650 | 1,667 | -0.3% | 986 | 2 | City |
| Riley | 3 | 956 | 941 | 0% | 1,882 | 1 | City |
| Leonardville | 4 | 443 | 431 | 0.23% | 1,448 | 0 | City |
| Randolph | 5 | 158 | 160 | -0.63% | 575 | 0 | City |
Manhattan is the largest city in Riley County, with a population of 54,699.
Randolph is the smallest city in Riley County, with a population of 158.
There are 5 cities in Riley County, Kansas.