18 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| McLeansboro township | 1 | 3,565 | 3,677 | -0.92% | 100 | 35.58 | Township |
| Dale township | 2 | 1,212 | 1,232 | -0.57% | 35 | 34.56 | Township |
| Dahlgren township | 3 | 1,112 | 1,147 | -0.89% | 20 | 54.30 | Township |
| Knight Prairie township | 4 | 517 | 533 | -0.96% | 14 | 36.30 | Township |
| Dahlgren | 5 | 498 | 503 | -0.2% | 490 | 1.02 | Village |
| Twigg township | 6 | 478 | 491 | -0.83% | 13 | 36.30 | Township |
| Mayberry township | 7 | 435 | 446 | -0.91% | 8 | 54.62 | Township |
| Crouch township | 8 | 374 | 387 | -1.06% | 8 | 47.35 | Township |
| Flannigan township | 9 | 306 | 313 | -0.65% | 8 | 36.20 | Township |
| Broughton township | 10 | 293 | 302 | -0.68% | 8 | 35.24 | Township |
| Crook township | 11 | 288 | 287 | 0% | 8 | 35.62 | Township |
| Beaver Creek township | 12 | 243 | 258 | -2.02% | 7 | 36.52 | Township |
| South Crouch township | 13 | 193 | 199 | -1.03% | 8 | 25.17 | Township |
| Broughton | 14 | 177 | 181 | -0.56% | 94 | 1.89 | Village |
| South Flannigan township | 15 | 134 | 140 | -1.47% | 7 | 18.34 | Township |
| South Twigg township | 16 | 126 | 121 | 0.8% | 7 | 18.35 | Township |
| Belle Prairie City | 17 | 48 | 50 | 0% | 110 | 0.44 | Town |
| Macedonia | 18 | 29 | 29 | 0% | 107 | 0.27 | Village |
McLeansboro township is the largest city in Hamilton County, with a population of 3,565.
Macedonia is the smallest city in Hamilton County.
There are 18 cities in Hamilton County, Illinois.