St. Clair County holds the southern half of the Illinois Metro-East, opposite downtown St. Louis. Its industrial history centers on East St. Louis — once a national hub for rail, meatpacking, aluminum, and heavy manufacturing — and the chemical corridor of Sauget and National City, where operations reportedly ran on asbestos-insulated steam, process, and power systems for most of the twentieth century. Workers across these plants, and the trades who serviced them, may have been exposed to asbestos-containing materials in boiler rooms, on process piping, and in furnace and refractory work.
Claims arising in St. Clair County are venued in the Twentieth Judicial Circuit, seated in Belleville. Along with neighboring Madison County, it forms the core of the Illinois Metro-East asbestos-litigation region.