15 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Hamilton | 1 | 2,621 | 2,743 | -0.76% | 736 | 4 | City |
| Carthage | 2 | 2,393 | 2,506 | -0.79% | 946 | 3 | City |
| Warsaw | 3 | 1,431 | 1,506 | -0.83% | 219 | 7 | City |
| La Harpe | 4 | 1,119 | 1,173 | -0.8% | 820 | 1 | City |
| Nauvoo | 5 | 895 | 939 | -0.78% | 264 | 3 | City |
| Dallas City | 6 | 763 | 808 | -0.91% | 321 | 2 | City |
| Augusta | 7 | 530 | 556 | -0.75% | 767 | 1 | Village |
| Bowen | 8 | 440 | 461 | -0.68% | 1,028 | 0 | Village |
| Plymouth | 9 | 414 | 434 | -0.72% | 733 | 1 | Village |
| Elvaston | 10 | 143 | 149 | -0.69% | 179 | 1 | Village |
| West Point | 11 | 133 | 142 | -0.75% | 792 | 0 | Village |
| Ferris | 12 | 117 | 126 | -0.85% | 59 | 2 | Village |
| Pontoosuc | 13 | 96 | 101 | -1.03% | 68 | 1 | Village |
| Basco | 14 | 76 | 79 | 0% | 342 | 0 | Village |
| Bentley | 15 | 25 | 27 | 0% | 175 | 0 | Town |
Hamilton is the largest city in Hancock County, with a population of 2,621.
Bentley is the smallest city in Hancock County, with a population of 25.
There are 15 cities in Hancock County, Illinois.