There are 16 cities in St. Charles County, Missouri.
City | Rank | State | 2023 Population | 2020 Census | Annual Change | Density (mi²) | Area (mi²) |
|---|---|---|---|---|---|---|---|
| O'Fallon | 1 | Missouri | 97,778 | 91,643 | 2.18% | 3,283 | 29.78 |
| St. Charles | 2 | Missouri | 71,339 | 70,562 | 0.37% | 2,874 | 24.82 |
| St. Peters | 3 | Missouri | 59,042 | 57,678 | 0.78% | 2,635 | 22.40 |
| Wentzville | 4 | Missouri | 46,591 | 44,893 | 1.24% | 2,338 | 19.93 |
| Lake St. Louis | 5 | Missouri | 18,398 | 16,792 | 3.09% | 2,156 | 8.53 |
| Dardenne Prairie | 6 | Missouri | 13,267 | 12,769 | 1.28% | 2,463 | 5.39 |
| Cottleville | 7 | Missouri | 5,896 | 5,695 | 1.17% | 1,277 | 4.62 |
| Weldon Spring | 8 | Missouri | 5,248 | 5,332 | -0.53% | 686 | 7.65 |
| St. Paul | 9 | Missouri | 3,839 | 3,061 | 7.84% | 539 | 7.12 |
| Flint Hill | 10 | Missouri | 863 | 817 | 1.89% | 269 | 3.21 |
| New Melle | 11 | Missouri | 534 | 540 | -0.37% | 317 | 1.68 |
| Josephville | 12 | Missouri | 518 | 515 | 0.19% | 198 | 2.61 |
| West Alton | 13 | Missouri | 354 | 357 | -0.28% | 12 | 28.81 |
| Portage Des Sioux | 14 | Missouri | 322 | 331 | -0.92% | 560 | 0.57 |
| Augusta | 15 | Missouri | 263 | 269 | -0.76% | 299 | 0.88 |
| Weldon Spring Heights | 16 | Missouri | 90 | 93 | -1.1% | 938 | 0.10 |
O'Fallon is the largest city in St. Charles County.
Weldon Spring Heights is the smallest city in St. Charles County.
There are 16 cities in St. Charles County, Missouri.