Primary Metal Manufacturing in Illinois

NAICS 331 · IL

This register lists 550 facilities in Illinois. The Bureau of Labor Statistics counted 336 establishments in the Primary Metal Manufacturing industry in Illinois in 2025. Mapleton Foundry in Mapleton employed 1,186 people in 2025.

SUMMARIZED FROM THE FEDERAL FIGURES ON THIS PAGE

Plants in Illinois18 FACILITIES

Listing 18 of 27: the facilities with a website, a size band or two sources on record. The rest are in site search.

Facility	City	Employees	Status
ASAlton Steel INC	Alton	100–499	● ACTIVE
HSHeidtman Steel Products INC	Granite City	20–99	● ACTIVE
MMMayco Manufacturing LLC dba Mayco Industries	Granite City	20–99	● ACTIVE
CSCustom Steel Processing (2)	Madison	20–99	◐ LIKELY ACTIVE
GCGranite City Works of United States Steel CORP	Granite City	—	◐ LIKELY ACTIVE
MMMayco Mfg LLC	Granite City	—	◐ LIKELY ACTIVE
SCSpectrulite Consortium Incorporated	Madison	—	◐ LIKELY ACTIVE
Wieland Rolled Products North America, LLC	East Alton	—	◐ LIKELY ACTIVE
ASAmerican Steel Foundries - Granite City	Granite City	—	◐ LIKELY ACTIVE
GEGateway Energy & Coke CO LLC	Granite City	—	◐ LIKELY ACTIVE
OWOlin Winchester LLC	East Alton	—	◐ LIKELY ACTIVE
WRWieland Rolled Products NA - East Alton Casting Plant	East Alton	—	◐ LIKELY ACTIVE
GCGranite City Steel	Granite City	1–19	◐ LIKELY ACTIVE
CChemetco	Hartford	—	◐ LIKELY ACTIVE
GCGranite City Works	Granite City	500+	◐ LIKELY ACTIVE
CSCustom Steel Processing, INC.	Granite City	—	◐ LIKELY ACTIVE
LSLaclede Steel Company	Madison	—	◇ UNVERIFIED
LSLapham-Hickey Steel Corp	Madison	20–99	◐ LIKELY ACTIVE

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