19 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Henry township | 1 | 2,554 | 2,565 | 0% | 175 | 14.60 | Township |
| Lacon township | 2 | 2,341 | 2,346 | 0.09% | 135 | 17.35 | Township |
| Henry | 3 | 2,303 | 2,325 | -0.17% | 1,282 | 1.80 | City |
| Lacon | 4 | 1,853 | 1,868 | -0.16% | 1,158 | 1.60 | City |
| Bennington township | 5 | 1,570 | 1,575 | 0.06% | 44 | 35.99 | Township |
| Toluca | 6 | 1,329 | 1,341 | -0.15% | 1,251 | 1.06 | City |
| Evans township | 7 | 1,168 | 1,174 | 0% | 31 | 37.08 | Township |
| Steuben township | 8 | 1,112 | 1,111 | 0.09% | 39 | 28.86 | Township |
| Washburn | 9 | 1,011 | 1,033 | -0.39% | 1,400 | 0.72 | Village |
| Wenona | 10 | 965 | 975 | -0.21% | 1,311 | 0.74 | City |
| Hopewell township | 11 | 501 | 496 | 0.4% | 15 | 33.81 | Township |
| Hopewell | 12 | 418 | 418 | 0% | 368 | 1.14 | Village |
| Richland township | 13 | 400 | 400 | 0% | 11 | 35.99 | Township |
| Varna | 14 | 374 | 374 | 0% | 1,259 | 0.30 | Village |
| Sparland | 15 | 364 | 364 | 0% | 636 | 0.57 | Village |
| Bell Plain township | 16 | 320 | 318 | 0.31% | 9 | 36.79 | Township |
| Whitefield township | 17 | 259 | 257 | 0.39% | 7 | 36.74 | Township |
| Saratoga township | 18 | 244 | 242 | 0.41% | 7 | 35.90 | Township |
| La Rose | 19 | 99 | 99 | 0% | 388 | 0.26 | Village |
Henry township is the largest city in Marshall County, with a population of 2,554.
La Rose is the smallest city in Marshall County.
There are 19 cities in Marshall County, Illinois.