31 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Dixon | 1 | 17,075 | 17,345 | -0.17% | 590 | 29 | Township |
| Dixon | 2 | 15,103 | 15,366 | -0.35% | 1,593 | 9 | City |
| Amboy | 3 | 2,756 | 2,820 | -0.25% | 78 | 35 | Township |
| Amboy | 4 | 2,211 | 2,276 | -0.58% | 367 | 6 | City |
| Franklin Grove | 5 | 1,199 | 1,227 | -0.33% | 45 | 27 | Township |
| Ashton | 6 | 1,130 | 1,158 | -0.18% | 63 | 18 | Township |
| South Dixon | 7 | 963 | 982 | -0.21% | 32 | 30 | Township |
| Ashton | 8 | 933 | 962 | -0.64% | 1,294 | 1 | Village |
| Franklin Grove | 9 | 870 | 898 | -0.68% | 2,091 | 0 | Village |
| Paw Paw | 10 | 800 | 827 | -0.74% | 1,336 | 1 | Village |
| Nelson | 11 | 752 | 764 | -0.27% | 33 | 23 | Township |
| Brooklyn | 12 | 682 | 696 | -0.29% | 19 | 36 | Township |
| Sublette | 13 | 675 | 688 | -0.15% | 18 | 37 | Township |
| Willow Creek | 14 | 623 | 636 | -0.32% | 18 | 35 | Township |
| Lee Center | 15 | 543 | 547 | 0.18% | 15 | 36 | Township |
| Alto | 16 | 516 | 527 | -0.39% | 15 | 35 | Township |
| Nachusa | 17 | 440 | 449 | -0.23% | 15 | 29 | Township |
| Sublette | 18 | 370 | 379 | -0.54% | 925 | 0 | Village |
| Harmon | 19 | 341 | 348 | -0.29% | 10 | 36 | Township |
| Paw Paw | 20 | 311 | 313 | 0.32% | 8 | 38 | Township |
| Lee | 21 | 307 | 312 | -0.32% | 1,551 | 0 | Village |
| Compton | 22 | 265 | 270 | -0.38% | 1,606 | 0 | Village |
| Lee | 23 | 260 | 258 | -0.38% | 7 | 38 | Township |
| May | 24 | 253 | 257 | 0% | 7 | 35 | Township |
| East Grove | 25 | 245 | 249 | 0% | 7 | 36 | Township |
| Steward | 26 | 222 | 227 | -0.45% | 1,682 | 0 | Village |
| Lee | 27 | 204 | 210 | -0.49% | 5 | 37 | Township |
| Coleta | 28 | 160 | 164 | -0.62% | 432 | 0 | Village |
| West Brooklyn | 29 | 127 | 131 | -0.78% | 1,351 | 0 | Village |
| Nelson | 30 | 124 | 128 | -0.8% | 347 | 0 | Village |
| Harmon | 31 | 116 | 119 | -0.85% | 532 | 0 | Village |
Dixon is the largest city in Lee County, with a population of 17,075.
Harmon is the smallest city in Lee County, with a population of 116.
There are 31 cities in Lee County, Illinois.