| 1110 | Natural gas well | |
| 1120 | Natural gas well drilling, contract | |
| 1110 | Natural gasoline production | |
| 1729 | Natural hard fiber fabrics (e.g., flax, jute, hemp, ramie), narrow woven, weaving | |
| 1711 | Natural hard fibre (e.g., flax, hemp, jute, ramie) spun yarns, manufacturing | |
| 1729 | Natural hard fibre fabrics (e.g., linen, jute, hemp, ramie), broad-woven, weaving | |
| 9232 | Natural history museums | |
| 7513 | Natural resource conservation programs, federal government | |
| 9199 | Natural resource preservation organizations | |
| 1410 | Natural sand, other than metal-bearing, manufacturing | |
| 9232 | Natural science museums | |
| 1110 | Natural sour gas processing, mining | |
| 9233 | Natural wonders, tourist attractions | |
| 1554 | Naturally carbonated water, purifying and bottling | |
| 9233 | Nature centres | |
| 9233 | Nature parks | |
| 9233 | Nature reserves | |
| 8519 | Naturopaths' offices | |
| 3312 | Nautical and navigational instrument, repair | |
| 3312 | Nautical instruments (except electronic), manufacturing | |
| 3312 | Nautical instruments (except electronic), manufacturing | |
| 3312 | Nautical instruments, electronic, manufacturing | |
| 3312 | Nautical systems and instruments, manufacturing | |
| 2927 | Naval artillery, manufacturing | |
| 7522 | Naval base | |
| 8511 | Naval hospital | |
| 3511 | Naval ships, building | |
| 2411 | Naval stores, gum or wood, manufacturing | |
| 8090 | Navigation and fisheries school | |
| 4520 | Navigation canal construction | |
| 5150 | Navigational equipment and devices, electronic, wholesale | |
| 3312 | Navigational instruments (except electronic), manufacturing | |
| 3312 | Navigational instruments, electronic, manufacturing | |
| 3312 | Navigational instruments, manufacturing | |
| 7522 | Navy | |
| 1553 | Near beer, brewing | |
| 5139 | Necklaces, precious metal, wholesale | |
| 1820 | Neckpieces, fur, manufacturing | |
| 1730 | Neckties, made in knitting mills | |
| 1810 | Neckties, men's and boys', made from purchased fabric | |