| Appco | Barberton | OH |
| Apple Creek State Hospital | Canton | OH |
| Appleton Papers | Dayton | OH |
| Appleton Papers | West Carrollton | OH |
| A. & P. Tea | Ironton | OH |
| Aquarium - Cincinnati | Cincinnati | OH |
| Arbuckle, Ryan & Company | Alliance | OH |
| Arbuckle, Ryan & Company | Toledo | OH |
| Arbuckle, Ryan & Company | Massillon | OH |
| Arby's | Bedford Heights | OH |
| Arby's | Parma | OH |
| Arby's | Cleveland | OH |
| Arby's | Parma Heights | OH |
| Arcade Building | Worthington | OH |
| Archer Daniels Midland | Ashtabula | OH |
| ARCO | Cleveland | OH |
| Aristech Chemical | Haverhill | OH |
| Aristech Chemical | Ironton | OH |
| Aristocraft | Cincinnati | OH |
| Arkview Federal Savings & Loan | Shaker Heights | OH |
| Arlington Junior High School | Arlington | OH |
| Armature Coil | Cleveland | OH |
| ARMCO | Ashland | OH |
| ARMCO | Mansfield | OH |
| ARMCO | Dayton | OH |
| ARMCO | Marion | OH |
| ARMCO | Hamilton | OH |
| ARMCO | Zanesville | OH |
| ARMCO | Middletown | OH |
| ARMCO | New Miami | OH |
| ARMCO | Middleton | OH |
| Armour & Company | Alliance | OH |
| Armstrong Cork & Insulation | Columbus | OH |
| Armstrong Cork & Insulation | Cleveland | OH |
| Arnold, Hoffman & Company | Cincinnati | OH |
| Arrow Aluminum | Cleveland | OH |
| Arrow Aluminum | Avon Lake | OH |
| Art Galvanizing | Cleveland | OH |
| Arthur G. McKee & Company | Cleveland | OH |
| Arwood | Cleveland | OH |
| Asarco | Columbus | OH |
| Asbestos Covering & Roofing | Hamilton | OH |
| Asbestos Service | Youngstown | OH |
| Asbestos Service | Warren | OH |
| Asbestos Service | Columbus | OH |
| Asbestos Service | Worthington | OH |
| A. Schulman | Akron | OH |
| Ashland Chemical | South Point | OH |
| Ashland Chemical | Columbus | OH |
| Ashland Chemical | Dublin | OH |
