RANK #260 / 996 · POP 256,791 · IL
PROJECTED GROWTH: +1.7%
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.
Well below national median
Below-average climate & terrain
Housing looks undervalued at 3.2x — home prices are low relative to local economic output. The typical U.S. county is 4–6x.
Source: Redfin · Census BPS — Browse sales on Redfin →
| 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 996 counties.
St. Clair County has a Boom Town Index score of 74/100, ranking #260 among 996 U.S. counties. With job growth at -0.1% and a median household income of $68,915, it's an above-average county on economic indicators.
The median home value in St. Clair County is $158,500 with median rent at $1,002/month. The income-to-home-value ratio is 0.4348, which is more affordable than the national average.
Population growth: -0.7% year-over-year. Job growth: -0.1%. Home values changed +4.5% in the past 12 months.