There are 12 cities in Monroe County, Illinois.
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 |
|---|---|---|---|---|---|---|---|
| Waterloo | 1 | 11,190 | 11,005 | 0.41% | 1,359 | 8.2 | City |
| Columbia | 2 | 10,899 | 11,033 | -0.31% | 1,033 | 10.6 | City |
| Dupo | 3 | 3,769 | 3,976 | -1.36% | 589 | 6.4 | Village |
| Red Bud | 4 | 3,735 | 3,794 | -0.4% | 1,424 | 2.6 | City |
| New Athens | 5 | 1,848 | 1,947 | -1.33% | 875 | 2.1 | Village |
| Valmeyer | 6 | 1,206 | 1,228 | -0.5% | 352 | 3.4 | Village |
| Prairie Rocher | 7 | 512 | 500 | 0.59% | 897 | 0.6 | Village |
| Hecker | 8 | 414 | 428 | -0.96% | 1,551 | 0.3 | Village |
| Ruma | 9 | 309 | 312 | -0.32% | 416 | 0.7 | Village |
| Maeystown | 10 | 147 | 149 | -0.68% | 498 | 0.3 | Village |
| Floraville | 11 | 26 | 30 | 8.33% | 329 | 0.1 | CDP |
| Fults | 12 | 24 | 26 | -4% | 453 | 0.1 | Village |
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.
Waterloo is the largest city in Monroe County.
Fults is the smallest city in Monroe County.
There are 12 cities in Monroe County, Illinois.