11 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Sterling | 1 | 14,287 | 14,839 | -0.76% | 2,403 | 5.95 | City |
| Rock Falls | 2 | 8,487 | 8,769 | -0.66% | 2,131 | 3.98 | City |
| Morrison | 3 | 3,923 | 4,067 | -0.73% | 1,558 | 2.52 | City |
| Fulton | 4 | 3,514 | 3,646 | -0.73% | 1,503 | 2.34 | City |
| Prophetstown | 5 | 1,878 | 1,942 | -0.69% | 1,403 | 1.34 | City |
| Erie | 6 | 1,465 | 1,515 | -0.68% | 1,062 | 1.38 | Village |
| Albany | 7 | 838 | 857 | -0.47% | 782 | 1.07 | Village |
| Tampico | 8 | 664 | 693 | -0.9% | 1,685 | 0.39 | Village |
| Lyndon | 9 | 518 | 535 | -0.58% | 684 | 0.76 | Village |
| Galt | 10 | 142 | 204 | 6.77% | 486 | 0.29 | CDP |
| Deer Grove | 11 | 37 | 36 | 0% | 90 | 0.41 | Village |
Sterling is the largest city in Whiteside County, with a population of 14,287.
Deer Grove is the smallest city in Whiteside County.
There are 11 cities in Whiteside County, Illinois.