28 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Benton township | 1 | 18,645 | 19,028 | -0.39% | 1,317 | 14.16 | Township |
| Benton township | 2 | 8,563 | 8,719 | -0.17% | 237 | 36.13 | Township |
| West Frankfort | 3 | 7,073 | 7,253 | -0.51% | 1,419 | 4.98 | City |
| Benton | 4 | 6,533 | 6,695 | -0.49% | 1,190 | 5.49 | City |
| Denning township | 5 | 4,645 | 4,730 | -0.19% | 130 | 35.85 | Township |
| Tyrone township | 6 | 4,598 | 4,690 | -0.22% | 130 | 35.40 | Township |
| Six Mile township | 7 | 3,468 | 3,523 | -0.12% | 96 | 36.14 | Township |
| Logan township | 8 | 3,169 | 3,242 | -0.19% | 87 | 36.57 | Township |
| Christopher | 9 | 2,605 | 2,684 | -0.61% | 1,606 | 1.62 | City |
| Goode township | 10 | 2,589 | 2,635 | -0.15% | 93 | 27.94 | Township |
| McLeansboro | 11 | 2,587 | 2,644 | -0.42% | 943 | 2.74 | City |
| Sesser | 12 | 1,838 | 1,885 | -0.49% | 1,784 | 1.03 | City |
| Cave township | 13 | 1,660 | 1,679 | 0% | 46 | 35.76 | Township |
| Zeigler | 14 | 1,458 | 1,482 | -0.34% | 1,073 | 1.36 | City |
| Ewing township | 15 | 1,307 | 1,334 | -0.23% | 36 | 35.90 | Township |
| Royalton | 16 | 1,031 | 1,061 | -0.58% | 925 | 1.11 | Village |
| West City | 17 | 633 | 652 | -0.63% | 394 | 1.61 | Village |
| Eastern township | 18 | 571 | 581 | -0.17% | 16 | 36.14 | Township |
| Valier | 19 | 537 | 557 | -0.74% | 478 | 1.12 | Village |
| Barren township | 20 | 533 | 543 | -0.19% | 25 | 20.96 | Township |
| North City | 21 | 497 | 509 | -0.4% | 229 | 2.17 | Village |
| Thompsonville | 22 | 476 | 485 | -0.42% | 234 | 2.03 | Village |
| Northern township | 23 | 449 | 455 | 0% | 12 | 36.47 | Township |
| Buckner | 24 | 395 | 405 | -0.5% | 453 | 0.87 | Village |
| Orient | 25 | 317 | 327 | -0.63% | 426 | 0.74 | City |
| Hanaford | 26 | 312 | 319 | -0.32% | 310 | 1.01 | Village |
| Ewing | 27 | 292 | 299 | -0.34% | 289 | 1.01 | Village |
| Mulkeytown | 28 | 55 | 128 | -12.7% | 200 | 0.28 | CDP |
Benton township is the largest city in Franklin County, with a population of 18,645.
Mulkeytown is the smallest city in Franklin County.
There are 28 cities in Franklin County, Illinois.