| American Steel Foundries | Alliance | OH |
| American Steel Hoop | Girard | OH |
| American Steel Hoop | Youngstown | OH |
| American Steel & Wire | Canton | OH |
| American Steel & Wire | Cleveland | OH |
| American Steel & Wire | Marion | OH |
| American Stove | Lorain | OH |
| American Stove | Cleveland | OH |
| American Strawboard | Circleville | OH |
| American Strawboard | Lima | OH |
| American Strawboard | Barberton | OH |
| American Structural Products | Toledo | OH |
| American Suede Shoe | Toledo | OH |
| American Tank | Cleveland | OH |
| American Tobacco | Middletown | OH |
| American Tool Works | Cincinnati | OH |
| American Viscose | Marietta | OH |
| American Welding & Manufacturing | Warren | OH |
| American Welding & Manufacturing | Niles | OH |
| American Welding & Manufacturing | Youngstown | OH |
| American Weldless Steel Tube | Toledo | OH |
| American Wire Mills | Cleveland | OH |
| American Works | Cleveland | OH |
| American Zinc & Chemical | Columbus | OH |
| A.M. Higley | Cleveland | OH |
| Amweld Buildings Products | Niles | OH |
| Anaconda Industries | Gnadenhutten | OH |
| Anchor Hocking Glass | Lancaster | OH |
| Anchor Packing | Warren | OH |
| Anderson - IBEC | Strongsville | OH |
| Anderson Millwright Service | Cleveland | OH |
| Andrew Jergens | Cincinnati | OH |
| Andrew Plocher | Dayton | OH |
| Andrews & Hitchcock Iron | Youngstown | OH |
| Andrews & Hitchcock Iron | Hubbard | OH |
| Andrews School For Girls | Willoughby | OH |
| Andrews Soap | Cincinnati | OH |
| Angel Jay L | Columbus | OH |
| Angel Jay L | Toledo | OH |
| Anheuser-Busch Brewery | Worthington | OH |
| Anheuser-Busch Brewery | Columbus | OH |
| Anna Dean Farm | Barberton | OH |
| Ann Arbor Railroad | Toledo | OH |
| Annchurst Village | Westerville | OH |
| Ansted & Burk | Springfield | OH |
| Anunciation Church | Cleveland | OH |
| Apex Smelting | Cleveland | OH |
| A. P. Green Industries | Oak Hill | OH |
| A. P. Green Industries | Twinsburg | OH |
| A.P.I. Instrument | Chesterland | OH |
