| 1421 | Amblygonite mining | |
| 3420 | Ambulance bodies, manufacturing | |
| 8519 | Ambulance service, road | |
| 8519 | Ambulance services (except air) | |
| 8519 | Ambulance services, air | |
| 3410 | Ambulances, assembling on purchased chassis | |
| 5010 | Ambulances, wholesale | |
| 8512 | Ambulatory surgical centres | |
| 1429 | Amethyst mining | |
| 3312 | Amino acid analyzers, laboratory type, manufacturing | |
| 2413 | Amino resins, manufacturing | |
| 2413 | Amino-aldehyde resins, manufacturing | |
| 2411 | Aminoanthraquinone, manufacturing | |
| 2411 | Aminoazobenzene, manufacturing | |
| 2411 | Aminoazotoluene, manufacturing | |
| 2411 | Aminophenol, manufacturing | |
| 5149 | Ammonia (except fertilizer material), wholesale | |
| 2412 | Ammonia, anhydrous or aqueous, manufacturing | |
| 2424 | Ammonia, household type, manufacturing | |
| 2412 | Ammonium chloride, manufacturing | |
| 2412 | Ammonium compounds, not specified elsewhere by process, manufacturing | |
| 2412 | Ammonium hydroxide, manufacturing | |
| 2412 | Ammonium molybdate, manufacturing | |
| 2412 | Ammonium nitrate, manufacturing | |
| 2411 | Ammonium perchlorate, manufacturing | |
| 2412 | Ammonium phosphates, manufacturing | |
| 4520 | Ammonium plants, construction | |
| 2412 | Ammonium sulfate, manufacturing | |
| 2411 | Ammonium thiosulfate, manufacturing | |
| 5150 | Ammunition (except sporting), wholesale | |
| 2927 | Ammunition (i.e., more than 30 mm; more than 1.18 inch), manufacturing | |
| 5139 | Ammunition and firearms, sporting, wholesale | |
| 3693 | Ammunition belts, sporting type, of all materials, manufacturing | |
| 2899 | Ammunition boxes, light gauge metal, manufacturing | |
| 2023 | Ammunition boxes, wood, manufacturing | |
| 2927 | Ammunition carts (i.e., 30 mm or less; 1.18 inch or less), manufacturing | |
| 2927 | Ammunition carts (i.e., more than 30 mm; more than 1.18 inch), manufacturing | |
| 2927 | Ammunition loading and assembling plants | |
| 5239 | Ammunition, retail | |
| 2927 | Ammunition, small arms (i.e., 30 mm or less; 1.18 inch or less), manufacturing | |