32 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Sugar Creek township | 1 | 6,647 | 6,636 | -0.21% | 182 | 36.51 | Township |
| Looking Glass township | 2 | 6,307 | 6,455 | -0.63% | 125 | 50.38 | Township |
| Breese township | 3 | 5,424 | 5,572 | -0.79% | 145 | 37.38 | Township |
| Breese | 4 | 4,558 | 4,663 | -0.46% | 1,706 | 2.67 | City |
| Brookside township | 5 | 4,358 | 4,430 | -0.43% | 179 | 24.31 | Township |
| Carlyle township | 6 | 3,727 | 3,828 | -0.69% | 209 | 17.81 | Township |
| New Baden | 7 | 3,327 | 3,419 | -0.54% | 1,823 | 1.82 | Village |
| Carlyle | 8 | 3,162 | 3,249 | -0.53% | 923 | 3.42 | City |
| Trenton | 9 | 2,615 | 2,682 | -0.49% | 1,389 | 1.88 | City |
| Aviston | 10 | 2,469 | 2,351 | 0.98% | 1,543 | 1.60 | Village |
| Germantown township | 11 | 2,159 | 2,089 | 0.65% | 56 | 38.27 | Township |
| Wade township | 12 | 1,639 | 1,660 | -0.43% | 57 | 28.89 | Township |
| St. Rose township | 13 | 1,437 | 1,440 | -0.28% | 38 | 37.51 | Township |
| Germantown | 14 | 1,395 | 1,329 | 0.94% | 1,368 | 1.02 | Village |
| Santa Fe township | 15 | 1,197 | 1,196 | -0.17% | 47 | 25.52 | Township |
| Albers | 16 | 1,105 | 1,134 | -0.54% | 1,114 | 0.99 | Village |
| Central City | 17 | 1,060 | 1,100 | -0.75% | 1,876 | 0.56 | Village |
| Irishtown township | 18 | 1,035 | 1,030 | -0.19% | 41 | 24.95 | Township |
| Wamac | 19 | 951 | 981 | -0.63% | 672 | 1.42 | City |
| Beckemeyer | 20 | 906 | 920 | -0.33% | 1,468 | 0.62 | Village |
| Lake township | 21 | 801 | 820 | -0.74% | 27 | 29.79 | Township |
| Bartelso | 22 | 635 | 629 | 0.16% | 967 | 0.66 | Village |
| Damiansville | 23 | 544 | 563 | -0.73% | 662 | 0.82 | Village |
| Junction City | 24 | 515 | 527 | -0.39% | 753 | 0.68 | Village |
| Meridian township | 25 | 504 | 500 | 0% | 14 | 36.79 | Township |
| St. Rose | 26 | 462 | 459 | 0.22% | 782 | 0.59 | Village |
| Clement township | 27 | 450 | 450 | -0.22% | 24 | 18.83 | Township |
| Wheatfield township | 28 | 439 | 442 | -0.45% | 12 | 35.42 | Township |
| Hoffman | 29 | 428 | 440 | -0.47% | 846 | 0.51 | Village |
| Keyesport | 30 | 402 | 404 | 0% | 558 | 0.72 | Village |
| East Fork township | 31 | 357 | 353 | 0% | 11 | 31.57 | Township |
| Huey | 32 | 156 | 161 | -0.64% | 722 | 0.22 | Village |
Sugar Creek township is the largest city in Clinton County, with a population of 6,647.
Huey is the smallest city in Clinton County.
There are 32 cities in Clinton County, Illinois.