RANK #779 / 1001 NAT · #26 / 28 IL · POP 253,694
1YR FORECAST: +0.8%
5YR OUTLOOK: +24%
Home to the Cahokia Mounds State Historic Site, a UNESCO World Heritage site, St. Clair County, Illinois, offers a blend of historical significance and modern living. Located directly east of St. Louis, Missouri, the county provides residents with various commute options, including the MetroLink light rail system and bus routes, connecting them to the wider St. Louis metropolitan area. The community offers numerous parks and recreational facilities, such as Belleville's Bicentennial Park and Shiloh's Engelmann Farm Park, providing walking trails and green spaces.
Life in the county is characterized by a mix of families and young professionals, with many residents owning their homes. Public schools in towns like O'Fallon and Mascoutah are noted for their quality. The economy is driven by sectors such as healthcare, manufacturing, and transportation, with Scott Air Force Base and MidAmerica St. Louis Airport serving as significant employers. Recent economic developments include investments in infrastructure and manufacturing, alongside efforts to support local businesses and community transitions.
St. Clair County is one of 145 U.S. counties in this market profile — weaker than typical on the BoomTown Index. Within this cohort, its recent home-price change of +3.4% runs below the profile's typical +4.9%.
See all 145 Heartland Steady Growth counties →Overvalued relative to economy
Below-average climate & terrain
Housing looks overvalued at 8.6x — home prices are high relative to local economic output. The typical U.S. county is 4–6x.
Estimated local headcount ranges. Larger employers shown as floor + "+"; smaller employers show exact counts where reported.
Bars show trailing 12-month growth. The dashed Forecast bars are the model's next-12-month projection; the whisker marks the ±1% range (cooling–accelerating).
Source: Redfin · Census BPS — Browse sales on Redfin →
Source: CDC/NCHS vital statistics via County Health Rankings (2020–2022 avg). Rates per 100,000 population. Grade based on homicide rate relative to national average (~6.3). Learn more →
| PROJECT | AMOUNT | STATUS |
|---|---|---|
|
IDOT Highway and Multimodal Multi-Year Program (FY2025-2029)
Illinois Department of Transportation (IDOT)
|
$1,422M | Planned |
|
Cloverleaf Infrastructure Data Center Network (Metro East)
Cloverleaf Infrastructure
|
$500M | Proposed |
|
Bee Hollow Solar Project
Geronimo Power
|
$150M | Under Construction |
|
Herzog Battery Storage Project
Undisclosed (MISO interconnection queue)
|
$150M | Planned |
|
I-255 Resurfacing, Bridge and Ramp Repairs
Illinois Department of Transportation (IDOT)
|
$74M | Planned |
|
I-64 Widening, Resurfacing, Interchange Improvements and Bridge Repairs
Illinois Department of Transportation (IDOT)
|
$52M | Planned |
Source: public records, news, corporate announcements. Amounts are estimates where noted.
Bars show percentile rank among all 1001 counties.
At 22/100, St. Clair County faces headwinds that place it in the lower third of the 1001 counties we track. Median income of $73,854 combined with job growth of -0.5% suggests the local economy is struggling to keep pace with national trends.
By national standards, St. Clair County is quite affordable. Homes here have a median value of $180,300, and the income-to-home-value ratio of 0.41 is well above the U.S. average — especially with median rent at just $1,090/month. Residents can generally buy a home without being cost-burdened.
Population and employment in St. Clair County are both close to flat — population -0.4% YoY and jobs -0.5%. Home values shifted +3.4% over the past 12 months. A steady-state county, neither expanding quickly nor shrinking.
Not particularly — 1.8% of St. Clair County's population moved in from another state, which is below the national average. Most residents are long-term locals rather than recent transplants.