13 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Canton | 1 | 2,740 | 2,773 | -0.25% | 1,199 | 2 | City |
| Canton | 2 | 2,740 | 2,773 | -0.25% | 1,199 | 2 | City |
| La Grange | 3 | 801 | 824 | -0.62% | 515 | 2 | City |
| La Grange | 4 | 801 | 825 | -0.62% | 515 | 2 | City |
| La Belle | 5 | 641 | 661 | -0.62% | 943 | 1 | City |
| La Belle | 6 | 641 | 661 | -0.62% | 943 | 1 | City |
| Lewistown | 7 | 505 | 520 | -0.59% | 1,008 | 1 | Town |
| Lewistown | 8 | 505 | 520 | -0.59% | 1,008 | 1 | Town |
| Ewing | 9 | 392 | 402 | -0.51% | 628 | 1 | City |
| Ewing | 10 | 392 | 402 | -0.51% | 628 | 1 | City |
| Monticello | 11 | 104 | 107 | -0.95% | 398 | 0 | Village |
| Monticello | 12 | 104 | 107 | -0.95% | 398 | 0 | Village |
| Williamstown | 13 | 50 | 84 | 6.38% | 185 | 0 | CDP |
Canton is the largest city in Lewis County, with a population of 2,740.
Williamstown is the smallest city in Lewis County, with a population of 50.
There are 13 cities in Lewis County, Missouri.