| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| West Frankfort | 1 | 7,070 | 7,257 | -0.49% | 1,419 | 5 | City |
| Benton | 2 | 6,525 | 6,699 | -0.5% | 1,189 | 5 | City |
| Christopher | 3 | 2,590 | 2,678 | -0.65% | 1,597 | 2 | City |
| McLeansboro | 4 | 2,573 | 2,634 | -0.46% | 938 | 3 | City |
| Sesser | 5 | 1,882 | 1,894 | -0.32% | 1,827 | 1 | City |
| Zeigler | 6 | 1,450 | 1,482 | -0.41% | 1,067 | 1 | City |
| Royalton | 7 | 1,025 | 1,058 | -0.58% | 919 | 1 | Village |
| West City | 8 | 636 | 657 | -0.63% | 396 | 2 | Village |
| Valier | 9 | 535 | 552 | -0.56% | 476 | 1 | Village |
| North City | 10 | 500 | 509 | -0.6% | 230 | 2 | Village |
| Thompsonville | 11 | 475 | 485 | -0.42% | 234 | 2 | Village |
| Buckner | 12 | 390 | 403 | -0.76% | 447 | 1 | Village |
| Orient | 13 | 319 | 329 | -0.62% | 428 | 1 | City |
| Hanaford | 14 | 313 | 321 | -0.63% | 311 | 1 | Village |
| Ewing | 15 | 293 | 301 | -0.68% | 290 | 1 | Village |
West Frankfort is the largest city in Franklin County, with a population of 7,070.
Ewing is the smallest city in Franklin County, with a population of 293.
There are 15 cities in Franklin County, Illinois.