| Ashland College | Ashland | OH |
| Ashland High School | Ashland | OH |
| Ashland Oil & Refinery | Ashland | OH |
| Ashland Oil & Refinery | Canton | OH |
| Ashland Oil & Refinery | Lima | OH |
| Ashland Oil & Refinery | Findlay | OH |
| Ashland Oil & Refinery | South Point | OH |
| Ashland Oil & Refinery | North Bend | OH |
| Ashland Oil & Refinery | Belpre | OH |
| Ashtabula County Medical Center | Ashtabula | OH |
| Ashtabula General Hospital | Ashtabula | OH |
| Ashtabula Power Plant | Ashtabula | OH |
| Ashtabula Scrap & Reclamation Plant | Ashtabula | OH |
| Ashtabula Tele | Ashtabula | OH |
| Ashtabula Water Supply | Ashtabula | OH |
| Asphalt Block Pavement | Toledo | OH |
| Associated Sheet Metal | Cleveland | OH |
| A.S. Taft Power Building | Cincinnati | OH |
| Athens State Hospital | Athens | OH |
| Atkins & Pearce Manufacturing | Cincinnati | OH |
| Atlantic Foundry | Akron | OH |
| Atlas Car | Cleveland | OH |
| Atlas Foundry & Machine | Cleveland | OH |
| Atlas Laundry-Linen Supply | Columbus | OH |
| Atlas Underwear | Piqua | OH |
| Atmospheric Nitrogen | South Point | OH |
| Atomic Energy Commission | Chillicothe | OH |
| Atomic Energy Commission | Piketon | OH |
| AT&T | Sandusky | OH |
| AT&T | Medina | OH |
| AT&T | Portsmouth | OH |
| Auglaize Box Board | Saint Marys | OH |
| August Wagner Breweries | Columbus | OH |
| Aultman | Canton | OH |
| Aultman Health Foundation | Canton | OH |
| Aultman Hospital | Canton | OH |
| Aultman & Taylor Machinery | Mansfield | OH |
| Ault & Wiborg | Norwood | OH |
| Ault & Wiborg | Cincinnati | OH |
| Austin Powder | Cleveland | OH |
| Automobile Club Of America | Cleveland | OH |
| Automotive Equipment | Westlake | OH |
| Auto Workers Credit Union | Mansfield | OH |
| Avco | Cincinnati | OH |
| Avco | Evendale | OH |
| Avco New Idea Farm Equipment | Coldwater | OH |
| Aventis Pharmaceuticals | Cincinnati | OH |
| Avon Lake Power Plant | Cleveland | OH |
| Avon Products | Springdale | OH |
| Avtron Manufacturing | Cleveland | OH |
