17 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Beardstown township | 1 | 6,471 | 6,711 | -0.32% | 252 | 25.64 | Township |
| Beardstown | 2 | 5,629 | 5,928 | -1.05% | 1,555 | 3.62 | City |
| Virginia township | 3 | 1,595 | 1,670 | -0.5% | 45 | 35.67 | Township |
| Virginia | 4 | 1,422 | 1,512 | -1.25% | 1,178 | 1.21 | City |
| Ashland township | 5 | 1,238 | 1,288 | -0.32% | 69 | 17.95 | Township |
| Ashland | 6 | 1,151 | 1,216 | -1.12% | 1,539 | 0.75 | Village |
| Bluff Springs township | 7 | 855 | 883 | -0.23% | 15 | 57.63 | Township |
| Lake Petersburg | 8 | 774 | 547 | 0.52% | 428 | 1.81 | CDP |
| Arenzville township | 9 | 724 | 754 | -0.55% | 20 | 36.72 | Township |
| Chandlerville | 10 | 501 | 531 | -1.18% | 631 | 0.79 | Village |
| Chandlerville township | 11 | 444 | 457 | 0% | 18 | 24.98 | Township |
| Arenzville | 12 | 342 | 364 | -1.16% | 445 | 0.77 | Village |
| Hagener township | 13 | 325 | 334 | 0% | 7 | 47.95 | Township |
| Sangamon Valley township | 14 | 313 | 325 | -0.32% | 8 | 39.64 | Township |
| Panther Creek township | 15 | 293 | 305 | -0.34% | 8 | 35.58 | Township |
| Philadelphia township | 16 | 191 | 199 | -0.52% | 5 | 36.22 | Township |
| Newmansville township | 17 | 63 | 65 | 0% | 4 | 17.79 | Township |
Beardstown township is the largest city in Cass County, with a population of 6,471.
Newmansville township is the smallest city in Cass County.
There are 17 cities in Cass County, Illinois.