| 3312 | Aeronautical navigational systems, electronic, manufacturing | |
| 3312 | Aeronautical systems and instruments (except electronic navigational), manufacturing | |
| 3312 | Aeronautical systems and instruments, electronic navigational, manufacturing | |
| 3312 | Aeronautical systems and instruments, manufacturing | |
| 4520 | Aeroplane hangars, construction | |
| 3530 | Aeroplanes, manufacturing | |
| 7495 | Aerosol can filling, on a job order or contract basis | |
| 2899 | Aerosol cans, manufacturing | |
| 7495 | Aerosol packaging services | |
| 2429 | Aerosol tire inflators, manufacturing | |
| 2912 | Aerosol valves, metal, manufacturing | |
| 2919 | Aftercoolers (i.e., heat exchangers), manufacturing | |
| 2424 | After-shave preparations, manufacturing | |
| 2423 | Agar culture media, manufacturing | |
| 2423 | Agar-agar grinding, manufacturing | |
| 1429 | Agate mining | |
| 8531 | Aged nursing home | |
| 6592 | Agencies of foreign banks (i.e., international trade financing) | |
| 6599 | Agency fund | |
| 6720 | Agency, insurance | |
| 7020 | Agency, real estate | |
| 7499 | Agents or managers for artists | |
| 7499 | Agents or managers for authors | |
| 7499 | Agents or managers for celebrities | |
| 7499 | Agents or managers for entertainers | |
| 7499 | Agents or managers for public figures | |
| 7499 | Agents or managers for sports figures | |
| 9301 | Agents, for laundries and dry cleaners | |
| 7020 | Agents, real estate | |
| 6309 | Agents, shipping (marine) | |
| 7499 | Agents, theatrical talent | |
| 2924 | Aggregate spreaders, manufacturing | |
| 5143 | Aggregate, wholesale | |
| 2423 | Aggressins (except in vitro), manufacturing | |
| 5150 | Agitators, crushers and classifiers, mine, wholesale | |
| 6592 | Agreement Corporations (i.e., international trade financing) | |
| 6603 | Agricultural (i.e., crop and livestock) insurance | |
| 8030 | Agricultural and vocational college | |
| 5149 | Agricultural chemical dusts and sprays, wholesale | |
| 5149 | Agricultural chemicals, wholesale | |