There are 29 cities in St. Clair County, Illinois.

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City
Rank
2024 Population
2020 Census
Annual Change
Density (mi²)
Area (mi²)
Belleville140,21342,261-1.33%1,73223.22
O'Fallon231,84032,303-0.47%2,07215.37
Collinsville323,59224,322-0.8%1,60014.74
East St. Louis417,36918,403-1.56%1,24813.91
Fairview Heights516,02616,665-0.92%1,40311.43
Shiloh614,83414,1101.15%1,34611.02
Swansea713,88414,353-0.81%2,1476.47
Columbia810,93211,031-0.17%1,06010.31
Mascoutah98,5228,738-0.65%8939.54
Lebanon104,5384,682-0.83%1,7062.66
Freeburg114,4854,585-0.49%6586.82
Caseyville124,3854,391-0.07%6047.26
Scott AFB134,0233,845 9324.32
Millstadt143,8914,065-1.14%1,1163.49
Smithton153,8644,002-1.05%8714.43
Dupo163,7673,976-1.41%5916.38
New Baden173,3543,420-0.47%1,8381.82
Madison183,0443,138-0.78%25012.19
Washington Park192,4682,573-1.08%9792.52
Fairmont City202,1432,255-1.38%3466.20
New Athens211,8511,947-1.33%8762.11
Marissa221,7291,830-1.48%2407.21
Brooklyn23619650-1.28%7630.81
St. Libory24609628-0.65%6270.97
Lenzburg25442466-1.56%3831.16
East Carondelet26367389-1.61%3121.18
Summerfield27329343-1.2%6650.49
Fayetteville28285296-1.38%9630.30
Sauget29130138-1.52%294.56
showing: 29 rows

Cities in St. Clair County, Illinois by Population (2024)

What is the largest city in St. Clair County, Illinois?

Belleville is the largest city in St. Clair County.

What is the smallest city in St. Clair County, Illinois?

Sauget is the smallest city in St. Clair County.

How many cities are in St. Clair County?

There are 29 cities in St. Clair County, Illinois.

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