| American Cyanamid | Michigan City | IN |
| American Fletcher National Bank | Indianapolis | IN |
| American Hoist & Derrick | Fort Wayne | IN |
| American Home Foods | La Porte | IN |
| American Hominy | Terre Haute | IN |
| American Hominy | Indianapolis | IN |
| American Hominy | Mount Vernon | IN |
| American Lawn Mower | Muncie | IN |
| American Maize Products | Hammond | IN |
| American Mechanical Contractors | Indianapolis | IN |
| American Oil | Whiting | IN |
| American Oil | East Chicago | IN |
| American Radiator & Standard Sanitary | Kokomo | IN |
| American Rockwool | Wabash | IN |
| American Safety Razor | La Porte | IN |
| American Seeding Machine | Richmond | IN |
| American Sheet & Tin Plate | Gary | IN |
| American Sheet & Tin Plate | Muncie | IN |
| American Sheet & Tin Plate | Elwood | IN |
| American Steel & Wire | Gary | IN |
| American Steel & Wire | East Chicago | IN |
| American Steel & Wire | Hammond | IN |
| American Steel & Wire | Anderson | IN |
| American Steel & Wire | Muncie | IN |
| American Strawboard | Noblesville | IN |
| American Works | Elwood | IN |
| Ami Metals | Bloomington | IN |
| Ami Metals | Michigan City | IN |
| Amoco | Whiting | IN |
| A & M Oil | Whiting | IN |
| Anaconda | Terre Haute | IN |
| Anaconda Lead Products | East Chicago | IN |
| Anaconda Wire & Cable | Marion | IN |
| Anaconda Wire & Cable | Anderson | IN |
| Anchor Hocking Glass | Winchester | IN |
| Anderson College | Anderson | IN |
| Anderson Municipal Power Plant | Anderson | IN |
| Angola Die Casting | Angola | IN |
| Angola High School | Angola | IN |
| Angola Railway & Power | Angola | IN |
| Anheuser-Busch Brewery | Indianapolis | IN |
| Anheuser-Busch Brewery | Lafayette | IN |
| Arbuckle, Ryan & Company | Marion | IN |
| Arbuckle, Ryan & Company | Lafayette | IN |
| Arbuckle, Ryan & Company | Jeffersonville | IN |
| Architectural Products | Connersville | IN |
| ARCO | Terre Haute | IN |
| ARCO | East Chicago | IN |
| ARCO | Elkhart | IN |
| Arctic Engineering | Gary | IN |
