| 3511 | Ultramarine manufacturing | |
| 3511 | Umber manufacturing | |
| 2902 | Umber mining | |
| 3909 | Umbrella covering manufacturing | |
| 3909 | Umbrella frame manufacturing | |
| 3909 | Umbrella handle, excluding gold or silver, manufacturing | |
| 3901 | Umbrella handle, gold or silver, manufacturing | |
| 3909 | Umbrella manufacturing | |
| 9519 | Umbrella repairing | |
| 1210 | Uncultivated seed collecting | |
| 3845 | Under-carriage, aircraft, manufacturing | |
| 3220 | Underclothing cutting and sewing | |
| 3909 | Undertakers' goods and supplies manufacturing | |
| 9599 | Undertaking service | |
| 3832 | Underwater sound equipment | |
| 3220 | Underwear cutting and sewing | |
| 3213 | Underwear knitting | |
| 8102 | Underwriter, stock and share issues | |
| 9100 | Unemployment insurance administration, governmental | |
| 3220 | Uniform hat and cap manufacturing | |
| 6200 | Uniform supply service, except laundered on contract basis | |
| 3213 | Union suit knitting | |
| 9600 | United nations | |
| 9399 | United nations association | |
| 9600 | United nations educational, scientific and cultural organization | |
| 3845 | Universal joint, aircraft, manufacturing | |
| 3829 | Universal joint, except for motor vehicle and aircraft, manufacturing | |
| 3843 | Universal joint, motor vehicle, manufacturing | |
| 9600 | Universal postal union | |
| 9310 | University | |
| 9399 | University club | |
| 9310 | University library | |
| 9320 | University research institute, not engaged in teaching | |
| 7123 | Unloading vessels | |
| 3119 | Unsweetened chocolate manufacturing | |
| 3320 | Upholstered chair manufacturing | |
| 3320 | Upholstered furniture manufacturing | |
| 3320 | Upholstering | |
| 3211 | Upholstery fabric manufacturing | |
| 3219 | Upholstery filling, except excelsior, manufacturing | |