| 5110 | Non-ferrous metal ores and concentrates, agents and brokers | |
| 2720 | Non-ferrous metals (except aluminum), smelting and primary refining | |
| 2720 | Non-ferrous metals (except copper, aluminum), smelting and refining, primary | |
| 5149 | Nonferrous metals scrap, wholesale | |
| 3710 | Non-ferrous metals, recovery of, from scrap | |
| 5142 | Non-ferrous ores and concentrates, wholesale | |
| 2211 | Non-fiction book, publishers | |
| 2211 | Non-fiction book, publishing | |
| 2211 | Non-fiction book, publishing and printing combined | |
| 2221 | Nonfiction books, printing without publishing | |
| 6599 | Non-financial intangible assets leasing | |
| 6603 | Non-life insurance (except health) | |
| 8532 | Non-medical home care for developmentally handicapped | |
| 5149 | Nonmetallic minerals and concentrates, crude (except petroleum), wholesale | |
| 2423 | Non-prescription drug preparations, manufacturing | |
| 7010 | Non-residential buildings, operators | |
| 6023 | Non-specialized freight transport, local | |
| 6603 | Non-specialized reinsurance carriers | |
| 5259 | Non-store retailing, direct sales (door-to-door) | |
| 1810 | Non-tailored coats and jackets, men's and boys' (e.g., ski suits, windbreakers), manufacturing | |
| 9211 | Non-theatrical motion picture production | |
| 1729 | Nonwoven fabric tapes, manufacturing | |
| 1729 | Nonwoven fabrics, manufacturing | |
| 1729 | Nonwoven felts, manufacturing | |
| 1549 | Noodle mixes, made from purchased dried ingredients | |
| 1544 | Noodle mixes, made in dry pasta plants | |
| 1544 | Noodles, dry, manufacturing | |
| 1544 | Noodles, fresh, manufacturing | |
| 1544 | Noodles, fried, manufacturing | |
| 8030 | Normal schools (teachers college) | |
| 3693 | Nose and ear plugs for swimming, manufacturing | |
| 3693 | Nose plugs, manufacturing | |
| 3699 | Notarial seals, metal, engraved, manufacturing | |
| 7411 | Notaries public | |
| 7411 | Notary services | |
| 3000 | Notebook computers, manufacturing | |
| 2109 | Notebooks (including mechanically bound by wire or plastic), made from purchased paper | |
| 2101 | Notebooks, made in paper mills | |
| 5239 | Notepaper and notebooks, retail | |
| 5232 | Notions and piece goods store, retail | |