| NRNucor Rebar Fabrication Fontana | Fontana | CA | — | ◇ UNVERIFIED |
| NRNucor Rebar Fabrication Northeast LLC | Pawtucket | RI | — | ◇ UNVERIFIED |
| NRNucor Rebar Fabrication Southwest INC | Lakeside | CA | — | ◇ UNVERIFIED |
| NRNucor Rebar Fabrication Southwest INC | Lathrop | CA | — | ◇ UNVERIFIED |
| NSNucor Skyline | Armorel | AR | — | ◇ UNVERIFIED |
| NTNucor Towers and Structures | New Ross | IN | — | ◇ UNVERIFIED |
| NTNucor Towers & Structures | Crawfordsville | IN | — | ◇ UNVERIFIED |
| NVNucor Vulcraft Group | San Antonio | TX | — | ◇ UNVERIFIED |
| NVNucor Vulcraft - St. Joe Division | Saint Joe | IN | — | ◇ UNVERIFIED |
| NSNuEra Steel LLC | Viborg | SD | — | ◇ UNVERIFIED |
| NCNueva Castilla Iron Works, INC. | San Francisco | CA | — | ◇ UNVERIFIED |
| NRNufab Rebar-slidell, LLC | Alexandria | LA | — | ◇ UNVERIFIED |
| NNNumber Nine, L.l.c. | Lk Havasu Cty | AZ | — | ◇ UNVERIFIED |
| NFNusteel Fabricators, INC. | Childersburg | AL | — | ◇ UNVERIFIED |
| NINutra-Boss Inc | Blue Earth | MN | — | ◇ UNVERIFIED |
| NSNWA Steel Co LLC | Siloam Springs | AR | — | ◇ UNVERIFIED |
| NINw Iron Works INC | Portland | OR | — | ◇ UNVERIFIED |
| NMNw Mixer Feeders | Caldwell | ID | — | ◇ UNVERIFIED |
| OIOakdale Iron Works, INC. | Oakdale | PA | — | ◇ UNVERIFIED |
| OFOberlin Filter Company | Pewaukee | WI | — | ◇ UNVERIFIED |
| OCObie Construction, INC. | Eugene | OR | — | ◇ UNVERIFIED |
| OMO'Brien Metal Inc. | Chicago | IL | — | ◇ UNVERIFIED |
| OOObrien Ornamental Iron INC | Minneapolis | MN | — | ◇ UNVERIFIED |
| OIOcci INC. Wwtp | Fulton | MO | — | ◇ UNVERIFIED |
 Occupational Development Center INC Dba Custom Pro | Bemidji | MN | — | ◇ UNVERIFIED |
| OSOcean Steel Corporation | Binghamton | NY | — | ◇ UNVERIFIED |
| OCOctober CO Chemetal Division | Easthampton | MA | — | ◇ UNVERIFIED |
| OBOeg Building Materials INC. | Matawan | NJ | — | ◇ UNVERIFIED |
| OFOem Fabricators INC | Neillsville | WI | — | ◇ UNVERIFIED |
| OIOesco INC | Conway | MA | — | ◇ UNVERIFIED |
| OSOesterlings Sandblasting/butler | Butler | PA | — | ◇ UNVERIFIED |
| OAOgden Art Metal INC. | Murray | UT | — | ◇ UNVERIFIED |
| OOgletree's | Saint Helena | CA | — | ◇ UNVERIFIED |
| OCOglivie Company INC the | Astoria | OR | — | ◇ UNVERIFIED |
| OHO H I Company | Stockton | CA | — | ◇ UNVERIFIED |
| OCOhi Company | Stockton | CA | — | ◇ UNVERIFIED |
| OSOhio Steel Industries (0145000318) | Pataskala | OH | — | ◇ UNVERIFIED |
| OSOhio Steel Industries, INC. | Summit Station | OH | — | ◇ UNVERIFIED |
| OVOhio Valley Fabrication and Energy INC. | Wheeling | WV | — | ◇ UNVERIFIED |
| OIOiw, INC. | Pelham | AL | — | ◇ UNVERIFIED |
| OLOiw LLC | Oakdale | PA | — | ◇ UNVERIFIED |
| OKO & K American CORP. | Chicago | IL | — | ◇ UNVERIFIED |
| OSOklahoma Stair Craft, INC. | Sapulpa | OK | — | ◇ UNVERIFIED |
| OBOld Bridge Metal Fabrication Inc. | Riverside | CA | — | ◇ UNVERIFIED |
| OIOldcastle Infrastructure - Azusa 10th | Azusa | CA | — | ◇ UNVERIFIED |
| OIOldcastle Infrastructure - Azusa Dalou | Azusa | CA | — | ◇ UNVERIFIED |
| OSOld South Ironworks INC | Gray | TN | — | ◇ UNVERIFIED |
| OWOld World Iron | Gilroy | CA | — | ◇ UNVERIFIED |
| OOOliver's Ornamental Iron, LLC | Flora | MS | — | ◇ UNVERIFIED |
| OCOlson & Company Steel | Fresno | CA | — | ◇ UNVERIFIED |
