There are 21 cities in St. Clair County, Missouri.
Note: As defined by the US Census Bureau, a city's official boundaries often extend miles beyond the city itself and may even cross county lines. As such, several thousand US cities officially exist in two or more counties (and therefore appear on multiple counties' lists of cities.)
City | Rank | 2024 Population | 2020 Population | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| El Dorado Springs | 1 | 3,625 | 3,504 | 0.83% | 1,176 | 3.1 | City |
| Warsaw | 2 | 2,365 | 2,216 | 1.59% | 949 | 2.5 | City |
| Stockton | 3 | 1,826 | 1,688 | 1.9% | 863 | 2.1 | City |
| Appleton City | 4 | 1,091 | 1,034 | 1.3% | 950 | 1.1 | City |
| Osceola | 5 | 983 | 935 | 1.24% | 911 | 1.1 | City |
| Humansville | 6 | 940 | 914 | 0.64% | 753 | 1.2 | City |
| Lowry City | 7 | 656 | 616 | 1.55% | 639 | 1.0 | City |
| Weaubleau | 8 | 401 | 379 | 1.26% | 464 | 0.9 | City |
| Montrose | 9 | 390 | 384 | 0.26% | 684 | 0.6 | City |
| Deepwater | 10 | 379 | 357 | 1.34% | 447 | 0.8 | City |
| Bent Tree Harbor | 11 | 356 | 220 | 7.88% | 171 | 2.1 | CDP |
| White Branch | 12 | 287 | 225 | 7.9% | 577 | 0.5 | CDP |
| Schell City | 13 | 225 | 228 | -0.44% | 362 | 0.6 | City |
| Rockville | 14 | 140 | 138 | 0% | 426 | 0.3 | City |
| Collins | 15 | 133 | 127 | 0.76% | 538 | 0.2 | Village |
| Roscoe | 16 | 96 | 91 | 1.05% | 63 | 1.5 | Village |
| Brownington | 17 | 71 | 69 | 0% | 587 | 0.1 | Town |
| Umber View Heights | 18 | 40 | 39 | 0% | 645 | 0.1 | Village |
| Vista | 19 | 36 | 34 | 0% | 275 | 0.1 | Village |
| Harwood | 20 | 31 | 31 | 0% | 295 | 0.1 | Village |
| Gerster | 21 | 16 | 15 | 0% | 198 | 0.1 | Town |
Note: City markers shown outside the county boundary mean that a part of the city extends into this county, but is primarily located in an adjacent county.
El Dorado Springs is the largest city in St. Clair County.
Gerster is the smallest city in St. Clair County.
There are 21 cities in St. Clair County, Missouri.