| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Freeport | 1 | 23,040 | 23,958 | -0.7% | 1,942 | 12 | City |
| Lena | 2 | 2,651 | 2,757 | -0.71% | 1,000 | 3 | Village |
| Pearl City | 3 | 755 | 781 | -0.66% | 1,169 | 1 | Village |
| Orangeville | 4 | 736 | 769 | -0.81% | 1,086 | 1 | Village |
| Cedarville | 5 | 641 | 668 | -0.77% | 1,390 | 0 | Village |
| Davis | 6 | 566 | 591 | -0.88% | 1,384 | 0 | Village |
| Dakota | 7 | 475 | 498 | -1.04% | 1,908 | 0 | Village |
| German Valley | 8 | 413 | 431 | -0.96% | 888 | 0 | Village |
| Rock City | 9 | 282 | 295 | -1.05% | 2,074 | 0 | Village |
| Winslow | 10 | 275 | 288 | -0.72% | 600 | 0 | Village |
| Ridott | 11 | 122 | 127 | -0.81% | 1,525 | 0 | Village |
Freeport is the largest city in Stephenson County, with a population of 23,040.
Ridott is the smallest city in Stephenson County, with a population of 122.
There are 11 cities in Stephenson County, Illinois.