32 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Galesburg City | 1 | 29,347 | 29,942 | 0.1% | 1,652 | 18 | Township |
| Galesburg | 2 | 28,962 | 29,942 | -0.56% | 1,631 | 18 | City |
| Knox | 3 | 4,860 | 4,928 | 0.21% | 137 | 35 | Township |
| Cedar | 4 | 2,988 | 3,055 | 0.13% | 83 | 36 | Township |
| Abingdon | 5 | 2,832 | 2,949 | -0.67% | 1,987 | 1 | City |
| Knoxville | 6 | 2,813 | 2,894 | -0.46% | 1,197 | 2 | City |
| Indian Point | 7 | 1,404 | 1,445 | -0.07% | 39 | 36 | Township |
| Henderson | 8 | 1,118 | 1,139 | 0.18% | 33 | 34 | Township |
| Persifer | 9 | 1,069 | 1,084 | 0.28% | 31 | 35 | Township |
| Ontario | 10 | 898 | 917 | 0.11% | 25 | 36 | Township |
| Truro | 11 | 835 | 855 | 0% | 23 | 36 | Township |
| East Galesburg | 12 | 735 | 761 | -0.54% | 538 | 1 | Village |
| Wataga | 13 | 714 | 741 | -0.56% | 861 | 1 | Village |
| Oneida | 14 | 673 | 696 | -0.59% | 882 | 1 | City |
| Walnut Grove | 15 | 660 | 677 | 0% | 19 | 36 | Township |
| Yates City | 16 | 630 | 651 | -0.47% | 1,278 | 0 | Village |
| Williamsfield | 17 | 550 | 570 | -0.54% | 447 | 1 | Village |
| Orange | 18 | 512 | 526 | -0.19% | 14 | 36 | Township |
| Rio | 19 | 505 | 515 | 0.2% | 14 | 36 | Township |
| Maquon | 20 | 452 | 463 | 0% | 13 | 36 | Township |
| Altona | 21 | 445 | 462 | -0.67% | 474 | 1 | Village |
| Copley | 22 | 386 | 391 | 0.52% | 11 | 35 | Township |
| Galesburg | 23 | 386 | 389 | 0.26% | 18 | 21 | Township |
| Victoria | 24 | 364 | 370 | 0.28% | 10 | 35 | Township |
| Haw Creek | 25 | 351 | 358 | 0.29% | 10 | 36 | Township |
| Lynn | 26 | 261 | 268 | 0% | 7 | 35 | Township |
| Victoria | 27 | 255 | 266 | -0.78% | 565 | 0 | Village |
| Henderson | 28 | 254 | 262 | -0.39% | 958 | 0 | Village |
| Elba | 29 | 246 | 257 | -0.81% | 7 | 36 | Township |
| Maquon | 30 | 211 | 222 | -0.94% | 1,302 | 0 | Village |
| Rio | 31 | 203 | 209 | -0.49% | 651 | 0 | Village |
| St. Augustine | 32 | 112 | 117 | -0.88% | 189 | 1 | Village |
Galesburg City is the largest city in Knox County, with a population of 29,347.
St. Augustine is the smallest city in Knox County, with a population of 112.
There are 32 cities in Knox County, Illinois.