48 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Watseka | 1 | 4,403 | 4,670 | -1.19% | 1,496 | 2.94 | City |
| Middleport township | 2 | 3,507 | 3,730 | -1.41% | 96 | 36.40 | Township |
| Chebanse township | 3 | 2,724 | 2,877 | -1.23% | 43 | 63.77 | Township |
| Belmont township | 4 | 2,289 | 2,429 | -1.38% | 63 | 36.32 | Township |
| Douglas township | 5 | 1,916 | 2,040 | -1.39% | 43 | 44.66 | Township |
| Gilman | 6 | 1,636 | 1,740 | -1.27% | 672 | 2.43 | City |
| Onarga township | 7 | 1,523 | 1,610 | -1.17% | 31 | 48.53 | Township |
| Milford township | 8 | 1,386 | 1,486 | -1.63% | 31 | 44.34 | Township |
| Loda township | 9 | 1,365 | 1,440 | -1.37% | 35 | 38.73 | Township |
| Ashkum township | 10 | 1,339 | 1,425 | -1.54% | 21 | 62.37 | Township |
| Clifton | 11 | 1,272 | 1,352 | -1.24% | 1,368 | 0.93 | Village |
| Onarga | 12 | 1,253 | 1,327 | -1.18% | 749 | 1.67 | Village |
| Sheldon township | 13 | 1,151 | 1,222 | -1.29% | 29 | 39.67 | Township |
| Milford | 14 | 1,084 | 1,159 | -1.36% | 1,615 | 0.67 | Village |
| Pigeon Grove township | 15 | 1,050 | 1,119 | -1.5% | 29 | 35.86 | Township |
| Chebanse | 16 | 991 | 1,046 | -1.1% | 833 | 1.19 | Village |
| Sheldon | 17 | 908 | 967 | -1.3% | 1,206 | 0.75 | Village |
| Danforth township | 18 | 840 | 889 | -1.29% | 16 | 51.65 | Township |
| Martinton township | 19 | 784 | 831 | -1.38% | 14 | 54.22 | Township |
| Artesia township | 20 | 779 | 831 | -1.52% | 14 | 57.37 | Township |
| Cissna Park | 21 | 762 | 812 | -1.3% | 1,051 | 0.72 | Village |
| Ashkum | 22 | 703 | 747 | -1.26% | 842 | 0.83 | Village |
| Ash Grove township | 23 | 618 | 651 | -1.28% | 10 | 61.03 | Township |
| Danforth | 24 | 562 | 594 | -1.06% | 1,176 | 0.48 | Village |
| Iroquois township | 25 | 522 | 554 | -1.32% | 14 | 36.28 | Township |
| Crescent City | 26 | 517 | 554 | -1.34% | 1,134 | 0.46 | Village |
| Crescent township | 27 | 505 | 536 | -1.37% | 14 | 36.42 | Township |
| Beaverville township | 28 | 481 | 509 | -1.23% | 13 | 37.80 | Township |
| Buckley | 29 | 459 | 491 | -1.29% | 1,453 | 0.32 | Village |
| Beaver township | 30 | 444 | 471 | -1.33% | 13 | 33.65 | Township |
| Sun River Terrace | 31 | 439 | 458 | -0.9% | 756 | 0.58 | Village |
| Papineau township | 32 | 415 | 439 | -1.43% | 14 | 29.49 | Township |
| Loda | 33 | 336 | 356 | -1.18% | 229 | 1.47 | Village |
| Woodland township | 34 | 325 | 340 | -1.22% | 9 | 37.96 | Township |
| Martinton | 35 | 313 | 335 | -1.26% | 1,142 | 0.27 | Village |
| Ridgeland township | 36 | 298 | 319 | -1.65% | 11 | 27 | Township |
| Beaverville | 37 | 285 | 305 | -1.38% | 1,036 | 0.28 | Village |
| Fountain Creek township | 38 | 279 | 301 | -2.11% | 8 | 36.23 | Township |
| Woodland township | 39 | 271 | 272 | 0% | 7 | 36.58 | Township |
| Woodland | 40 | 233 | 247 | -1.27% | 476 | 0.49 | Village |
| Donovan | 41 | 231 | 248 | -1.28% | 704 | 0.33 | Village |
| Thawville | 42 | 202 | 214 | -0.98% | 658 | 0.31 | Village |
| Stockland township | 43 | 192 | 200 | -1.03% | 4 | 53.51 | Township |
| Wellington | 44 | 190 | 204 | -1.55% | 798 | 0.24 | Village |
| Prairie Green township | 45 | 151 | 164 | -2.58% | 4 | 40.67 | Township |
| Milks Grove township | 46 | 149 | 162 | -2.61% | 4 | 36.35 | Township |
| Papineau | 47 | 128 | 135 | -0.78% | 615 | 0.21 | Village |
| Iroquois | 48 | 127 | 132 | -0.78% | 224 | 0.57 | Village |
Watseka is the largest city in Iroquois County, with a population of 4,403.
Iroquois is the smallest city in Iroquois County.
There are 48 cities in Iroquois County, Illinois.