8 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Atlantic | 1 | 6,700 | 6,782 | -0.25% | 808 | 8 | City |
| Griswold | 2 | 971 | 988 | -0.41% | 1,594 | 1 | City |
| Anita | 3 | 951 | 960 | -0.21% | 536 | 2 | City |
| Lewis | 4 | 357 | 359 | -0.28% | 707 | 1 | City |
| Massena | 5 | 351 | 356 | -0.28% | 512 | 1 | City |
| Cumberland | 6 | 248 | 248 | 0% | 400 | 1 | City |
| Marne | 7 | 109 | 108 | 0% | 194 | 1 | City |
| Wiota | 8 | 90 | 92 | -1.1% | 301 | 0 | City |
Atlantic is the largest city in Cass County, with a population of 6,700.
Wiota is the smallest city in Cass County, with a population of 90.
There are 8 cities in Cass County, Iowa.