The Steel Tube Institute

Chicago's wholesaler directory holds 38 listings, and every one lists phone number, so pick up phone and call two or three before driving anywhere. 34 of those also link out to a website, letting you check inventory first. None are verified yet, so treat details as a starting point, not gospel. Zip codes cluster: four listings each in 60603 and 60632, three in 60616 and 60654, fewer elsewhere.

None of these carry a Sponsored tag, since this category hasn't turned on paid placement in Chicago, so what loads here is plain directory order, not anyone's paid spot. If you run one of these wholesale operations and see a missing site link, you can claim listing and add it, which helps most outside the top zip clusters where fewer names show up for someone comparing options.