St. Clair County IL Information


St. Clair County Subdivisions

St. Clair County IL Data & Demographics (As of July 1, 2022)


Total Population 253,415 (100%)
Population in Households 248,783 (98.2%)
Population in Families 201,344 (79.5%)
Population in Group Quarters1 4,632 ( 1.8%)
Population Density 385
Diversity Index2 60


Median Household Income $63,308
Average Household Income $90,106
% of Income for Mortgage4 16%
Per Capita Income $36,395
Wealth Index5 82


Total HU (Housing Units) 114,561 (100%)
Owner Occupied HU 68,343 (59.7%)
Renter Occupied HU 33,676 (29.4%)
Vacant Housing Units 12,542 (10.9%)
Median Home Value $194,062
Average Home Value $203,373
Housing Affordability Index3 122


Total Households 102,019
Average Household Size 2.44
Family Households 66,587
Average Family Size 3.00
  1. Group Quarters - a place where people live or stay in a group living arrangement. Includes college residents halls, nursing facilities, military barracks, and correctional facilities.
  2. 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 races 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.
  3. The Housing Affordability Index base is 100 and represents a balance point where a resident with a median household income can normally qualify to purchase a median price home. Values above 100 indicate increased affordability, while values below 100 indicate decreased affordability.
  4. The % of Income for Mortgage quantifies the percentage of median household income dedicated to mortgage payments on a home priced at the median value (assuming a 30-year mortgage and a 20% down payment).
  5. The Wealth Index is based on a number of indicators of affluence including average household income and average net worth, but it also includes the value of material possessions and resources. It represents the wealth of the area relative to the national level. Values above or below 100 represent above-average wealth or below-average wealth compared to the national level.


2020-2022 2022-2027
Population -0.69% -0.42%
Households -0.48% -0.27%
Families   -0.34%
Median Household Income   4.00%
Per Capita Income   3.44%
Owner Occupied HU   0.04%


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, 2022 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 # 9 92nd
Population Density # 9 92nd
Median Household Income # 29 73rd
Housing Affordability Index # 8 8th
Per Capita Income # 24 77th
Diversity Index # 12 89th

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

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