| 1429 | Amosite, milled fibre, mining | |
| 3312 | Ampere-hour meters, manufacturing | |
| 2423 | Amphetamines, uncompounded, manufacturing | |
| 3230 | Amplifiers (e.g., auto, home, musical instrument, public address), manufacturing | |
| 3220 | Amplifiers (e.g., RF power, I-F), broadcast and studio equipment, manufacturing | |
| 3190 | Amplifiers, magnetic, pulse and maser, manufacturing | |
| 5233 | Amplifiers, retail (except musical instruments) | |
| 5139 | Amplifiers, speakers and related sound equipment, wholesale | |
| 4520 | Amusement and recreational buildings, construction | |
| 5139 | Amusement and sporting goods, wholesale | |
| 5110 | Amusement and sporting goods, wholesale agents and brokers | |
| 9249 | Amusement arcades | |
| 9219 | Amusement concession, operator | |
| 9249 | Amusement device (except gambling) concession operators | |
| 9249 | Amusement device (except gambling) parlours, coin-operated | |
| 9249 | Amusement devices (except gambling), operated in own facilities | |
| 7010 | Amusement facilities rental | |
| 3694 | Amusement machines, coin-operated, manufacturing | |
| 5150 | Amusement park equipment, wholesale | |
| 9219 | Amusement parks (i.e., theme parks, water parks) | |
| 9219 | Amusement rides, concession operators | |
| 7511 | Amusement tax, local administration | |
| 2411 | Amyl acetate, manufacturing | |
| 8512 | Anaesthetists' offices | |
| 2423 | Analgesic preparations, manufacturing | |
| 3000 | Analog computers, manufacturing | |
| 5150 | Analytical instruments (e.g., photometers, spectrographs, chromatographic), wholesale | |
| 3312 | Analyzers for testing electrical characteristics, manufacturing | |
| 3313 | Analyzers, industrial process control type, manufacturing | |
| 1410 | Andalusite mining | |
| 2899 | Andirons, manufacturing | |
| 3312 | Anemometers, manufacturing | |
| 3311 | Anesthesia apparatus, manufacturing | |
| 8512 | Anesthesiologists, offices of | |
| 2423 | Anesthetic preparations, manufacturing | |
| 2423 | Anesthetics, uncompounded, manufacturing | |
| 4520 | Angelstone, installation | |
| 2423 | Angiourographic diagnostic preparations, manufacturing | |
| 2899 | Angle irons, metal, manufacturing | |
| 2922 | Angle rings (i.e., machine tool accessory), manufacturing | |