17 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Breese | 1 | 4,612 | 4,663 | -0.17% | 1,726 | 3 | City |
| New Baden | 2 | 3,380 | 3,424 | -0.21% | 1,852 | 2 | Village |
| Carlyle | 3 | 3,191 | 3,241 | -0.25% | 932 | 3 | City |
| Trenton | 4 | 2,642 | 2,683 | -0.26% | 1,403 | 2 | City |
| Aviston | 5 | 2,475 | 2,352 | 0.86% | 1,547 | 2 | Village |
| Germantown | 6 | 1,415 | 1,330 | 1% | 1,387 | 1 | Village |
| Albers | 7 | 1,118 | 1,133 | -0.18% | 1,127 | 1 | Village |
| Central City | 8 | 1,050 | 1,101 | -0.76% | 1,858 | 1 | Village |
| Wamac | 9 | 955 | 985 | -0.52% | 675 | 1 | City |
| Beckemeyer | 10 | 925 | 919 | 0.11% | 1,499 | 1 | Village |
| Bartelso | 11 | 644 | 629 | 0.47% | 980 | 1 | Village |
| Damiansville | 12 | 554 | 566 | -0.36% | 674 | 1 | Village |
| Junction City | 13 | 519 | 531 | -0.38% | 759 | 1 | Village |
| St. Rose | 14 | 469 | 459 | 0.43% | 794 | 1 | Village |
| Hoffman | 15 | 428 | 436 | -0.23% | 846 | 1 | Village |
| Keyesport | 16 | 402 | 405 | 0% | 558 | 1 | Village |
| Huey | 17 | 161 | 164 | 0% | 745 | 0 | Village |
Breese is the largest city in Clinton County, with a population of 4,612.
Huey is the smallest city in Clinton County, with a population of 161.
There are 17 cities in Clinton County, Illinois.