42 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Montebello | 1 | 3,200 | 3,329 | -0.99% | 87 | 37 | Township |
| West Point | 2 | 3,070 | 3,198 | -0.58% | 86 | 36 | Township |
| Carthage | 3 | 2,853 | 2,976 | -1.14% | 71 | 40 | Township |
| Hamilton | 4 | 2,641 | 2,743 | -0.79% | 742 | 4 | City |
| Carthage | 5 | 2,412 | 2,506 | -0.78% | 954 | 3 | City |
| Warsaw | 6 | 1,443 | 1,506 | -0.89% | 221 | 7 | City |
| Warsaw | 7 | 1,438 | 1,506 | -1.24% | 221 | 7 | Township |
| La Harpe | 8 | 1,326 | 1,380 | -0.97% | 36 | 37 | Township |
| La Harpe | 9 | 1,128 | 1,173 | -0.79% | 827 | 1 | City |
| Nauvoo | 10 | 905 | 943 | -0.98% | 232 | 4 | Township |
| Nauvoo | 11 | 902 | 939 | -0.88% | 266 | 3 | City |
| Dallas City | 12 | 832 | 871 | -1.19% | 54 | 15 | Township |
| Dallas City | 13 | 770 | 808 | -1.03% | 324 | 2 | City |
| Augusta | 14 | 676 | 708 | -1.31% | 18 | 38 | Township |
| Chili | 15 | 588 | 612 | -1.01% | 16 | 38 | Township |
| St. Mary | 16 | 538 | 560 | -0.92% | 15 | 37 | Township |
| Augusta | 17 | 534 | 556 | -0.93% | 773 | 1 | Village |
| Bowen | 18 | 443 | 461 | -0.89% | 1,035 | 0 | Village |
| Sonora | 19 | 428 | 446 | -0.93% | 12 | 36 | Township |
| Plymouth | 20 | 417 | 434 | -0.95% | 738 | 1 | Village |
| Appanoose | 21 | 415 | 432 | -0.95% | 16 | 26 | Township |
| Prairie | 22 | 369 | 386 | -1.07% | 11 | 33 | Township |
| Pontoosuc | 23 | 323 | 339 | -1.52% | 17 | 18 | Township |
| Bear Creek | 24 | 307 | 320 | -0.65% | 8 | 36 | Township |
| Rock Creek | 25 | 303 | 317 | -0.98% | 8 | 36 | Township |
| St. Albans | 26 | 294 | 308 | -1.34% | 8 | 36 | Township |
| Harmony | 27 | 292 | 304 | -0.68% | 8 | 38 | Township |
| Rocky Run-Wilcox | 28 | 275 | 290 | -1.79% | 5 | 57 | Township |
| Walker | 29 | 275 | 288 | -1.08% | 7 | 38 | Township |
| Durham | 30 | 243 | 254 | -0.82% | 7 | 37 | Township |
| Hancock | 31 | 241 | 251 | -1.23% | 6 | 38 | Township |
| Pilot Grove | 32 | 235 | 247 | -1.26% | 6 | 37 | Township |
| Wythe | 33 | 233 | 247 | -2.1% | 6 | 38 | Township |
| Fountain Green | 34 | 232 | 244 | -1.28% | 6 | 38 | Township |
| Hamilton | 35 | 178 | 183 | -0.56% | 5 | 36 | Township |
| Elvaston | 36 | 144 | 149 | -0.69% | 180 | 1 | Village |
| West Point | 37 | 134 | 142 | -1.47% | 798 | 0 | Village |
| Ferris | 38 | 118 | 126 | -1.67% | 60 | 2 | Village |
| Pontoosuc | 39 | 97 | 101 | -1.02% | 69 | 1 | Village |
| Basco | 40 | 76 | 79 | -1.3% | 342 | 0 | Village |
| Bentley | 41 | 25 | 27 | -3.85% | 175 | 0 | Town |
| Niota | 42 | 16 | 85 | 6.67% | 31 | 1 | CDP |
Montebello is the largest city in Hancock County, with a population of 3,200.
Niota is the smallest city in Hancock County, with a population of 16.
There are 42 cities in Hancock County, Illinois.