19 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Henry | 1 | 2,498 | 2,563 | -0.91% | 171 | 15 | Township |
| Lacon | 2 | 2,288 | 2,344 | -0.87% | 132 | 17 | Township |
| Henry | 3 | 2,287 | 2,340 | -0.48% | 1,273 | 2 | City |
| Lacon | 4 | 1,829 | 1,871 | -0.49% | 1,143 | 2 | City |
| Bennington | 5 | 1,539 | 1,577 | -0.9% | 43 | 36 | Township |
| Toluca | 6 | 1,315 | 1,342 | -0.45% | 1,238 | 1 | City |
| Evans | 7 | 1,145 | 1,173 | -0.87% | 31 | 37 | Township |
| Steuben | 8 | 1,089 | 1,107 | -0.82% | 38 | 29 | Township |
| Washburn | 9 | 1,006 | 1,029 | -0.49% | 1,393 | 1 | Village |
| Wenona | 10 | 951 | 971 | -0.42% | 1,292 | 1 | City |
| Hopewell | 11 | 488 | 496 | -0.81% | 14 | 34 | Township |
| Hopewell | 12 | 414 | 419 | -0.24% | 365 | 1 | Village |
| Richland | 13 | 394 | 402 | -1.01% | 11 | 36 | Township |
| Varna | 14 | 371 | 376 | -0.27% | 1,249 | 0 | Village |
| Sparland | 15 | 354 | 358 | -0.28% | 619 | 1 | Village |
| Bell Plain | 16 | 314 | 318 | -0.32% | 9 | 37 | Township |
| Whitefield | 17 | 252 | 257 | -0.79% | 7 | 37 | Township |
| Saratoga | 18 | 237 | 242 | -0.84% | 7 | 36 | Township |
| La Rose | 19 | 97 | 99 | -1.02% | 380 | 0 | Village |
Henry is the largest city in Marshall County, with a population of 2,498.
La Rose is the smallest city in Marshall County, with a population of 97.
There are 19 cities in Marshall County, Illinois.