| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Olney | 1 | 8,281 | 8,693 | -0.79% | 1,195 | 7 | City |
| Noble | 2 | 605 | 631 | -0.66% | 595 | 1 | Village |
| Parkersburg | 3 | 183 | 187 | -0.54% | 222 | 1 | Village |
| Claremont | 4 | 157 | 163 | -0.63% | 198 | 1 | Village |
| Calhoun | 5 | 151 | 159 | -1.31% | 166 | 1 | Village |
Olney is the largest city in Richland County, with a population of 8,281.
Calhoun is the smallest city in Richland County, with a population of 151.
There are 5 cities in Richland County, Illinois.