28 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Benton | 1 | 18,966 | 18,926 | 0.38% | 1,340 | 14 | Township |
| Benton | 2 | 8,532 | 8,724 | -0.37% | 236 | 36 | Township |
| West Frankfort | 3 | 7,099 | 7,258 | -0.45% | 1,424 | 5 | City |
| Benton | 4 | 6,547 | 6,699 | -0.47% | 1,193 | 5 | City |
| Denning | 5 | 4,631 | 4,736 | -0.43% | 129 | 36 | Township |
| Tyrone | 6 | 4,572 | 4,690 | -0.44% | 129 | 35 | Township |
| Six Mile | 7 | 3,458 | 3,526 | -0.35% | 96 | 36 | Township |
| Logan | 8 | 3,232 | 3,243 | 0.5% | 88 | 37 | Township |
| Goode | 9 | 2,614 | 2,634 | 0.35% | 94 | 28 | Township |
| Christopher | 10 | 2,605 | 2,682 | -0.61% | 1,606 | 2 | City |
| McLeansboro | 11 | 2,578 | 2,651 | -0.58% | 940 | 3 | City |
| Sesser | 12 | 1,871 | 1,893 | -0.27% | 1,817 | 1 | City |
| Cave | 13 | 1,649 | 1,680 | -0.3% | 46 | 36 | Township |
| Zeigler | 14 | 1,461 | 1,481 | -0.27% | 1,075 | 1 | City |
| Ewing | 15 | 1,305 | 1,338 | -0.46% | 36 | 36 | Township |
| Royalton | 16 | 1,037 | 1,064 | -0.58% | 930 | 1 | Village |
| West City | 17 | 636 | 654 | -0.63% | 396 | 2 | Village |
| Eastern | 18 | 571 | 583 | -0.35% | 16 | 36 | Township |
| Valier | 19 | 535 | 554 | -0.74% | 476 | 1 | Village |
| Barren | 20 | 530 | 542 | -0.19% | 25 | 21 | Township |
| North City | 21 | 496 | 510 | -0.6% | 228 | 2 | Village |
| Thompsonville | 22 | 477 | 485 | -0.42% | 235 | 2 | Village |
| Northern | 23 | 444 | 455 | -0.22% | 12 | 36 | Township |
| Buckner | 24 | 395 | 407 | -0.75% | 453 | 1 | Village |
| Orient | 25 | 319 | 328 | -0.62% | 428 | 1 | City |
| Hanaford | 26 | 313 | 320 | -0.63% | 311 | 1 | Village |
| Ewing | 27 | 294 | 303 | -0.68% | 291 | 1 | Village |
| Mulkeytown | 28 | 55 | 128 | -12.7% | 200 | 0 | CDP |
Benton is the largest city in Franklin County, with a population of 18,966.
Mulkeytown is the smallest city in Franklin County, with a population of 55.
There are 28 cities in Franklin County, Illinois.