St. Clair County IL Information


St. Clair County Subdivisions

St. Clair County IL Data & Demographics (As of July 1, 2017)


Total Population 268,351
Daytime Population: Workers 114,914
Daytime Population: Residents 141,078
Total Daytime Population (TDP) 255,992
Ratio TDP/Total Population1 0.95
Population in Households 263,698
Population in Familes 215,194
Population in Group Qrtrs 4,653
Population Density2 408
Diversity Index3 54


Median Household Income $52,680
Average Household Income $72,027
Per Capita Income $28,525


Total Housing Units 118,136 (100%)
Owner Occupied HU 66,533 (56.3%)
Renter Occupied HU 37,688 (31.9%)
Vacant Housing Units 13,915 (11.8%)
Median Home Value $125,830
Average Home Value $159,482


Total Households 104,221
Average Household Size 2.53
Family Households 69,304
Average Family Size 3
  1. If the ratio of the TDP to Total Population is greater than 1, the location gains population during the day when commuting workers are present. If the ratio is less than 1, the location is more of a bedroom community where people commute to another place for work.
  2. Population Density = Total Population per square mile.
  3. The Diversity Index is a scale of 0 to 100 that represents the likelihood that two persons, chosen at random from the same area, belong to different race or ethnic groups. If an area's entire population belongs to one race AND one ethnic group, then the area has zero diversity. An area's diversity index increases to 100 when the population is evenly divided into two or more race/ethnic groups.


2010-2017 2017-2022
Population -0.09% -0.27%
Households -0.11% -0.28%
Families -0.27% -0.39%
Median Household Income   0.98%
Per Capita Income   2.3%


St. Clair County IL - Peer Comparisons by Rank and Percentile

The table below compares St. Clair County to the other 102 counties and county equivalents in Illinois by rank and percentile using July 1, 2017 data. The location Ranked # 1 has the highest value. A location that ranks higher than 75% of its peers would be in the 75th percentile of the peer group.

Variable Description Rank Percentile
Total Population # 8 93rd
Population Density # 8 93rd
Diversity Index # 10 91st
Median Household Income # 29 73rd
Per Capita Income # 28 74th

Additional comparisons and rankings can be made with a VERY EASY TO USE Illinois Census Data Comparison Tool.