| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Hamilton | 1 | 2,599 | 2,745 | -0.95% | 730 | 4 | City |
| Carthage | 2 | 2,371 | 2,495 | -0.92% | 938 | 3 | City |
| Warsaw | 3 | 1,421 | 1,505 | -1.04% | 218 | 7 | City |
| La Harpe | 4 | 1,114 | 1,171 | -0.89% | 817 | 1 | City |
| Nauvoo | 5 | 886 | 939 | -1.01% | 262 | 3 | City |
| Dallas City | 6 | 758 | 807 | -1.17% | 319 | 2 | City |
| Augusta | 7 | 526 | 555 | -0.94% | 761 | 1 | Village |
| Bowen | 8 | 437 | 461 | -0.91% | 1,021 | 0 | Village |
| Plymouth | 9 | 412 | 435 | -0.96% | 729 | 1 | Village |
| Elvaston | 10 | 139 | 148 | -1.42% | 174 | 1 | Village |
| West Point | 11 | 135 | 143 | -0.74% | 804 | 0 | Village |
| Ferris | 12 | 122 | 130 | -1.61% | 62 | 2 | Village |
| Pontoosuc | 13 | 91 | 95 | -1.09% | 65 | 1 | Village |
| Basco | 14 | 76 | 81 | -1.3% | 342 | 0 | Village |
| Bentley | 15 | 25 | 27 | -3.85% | 175 | 0 | Town |
Hamilton is the largest city in Hancock County, with a population of 2,599.
Bentley is the smallest city in Hancock County, with a population of 25.
There are 15 cities in Hancock County, Illinois.