| Code | Name | Region |
|---|---|---|
| USUNK | Unalakleet | AK |
| USUAA | Unalaska | AK |
| USUVL | Uncasville | CT |
| USUH2 | Underhill | VT |
| USUWD | Underwood | IA |
| USUND | Underwood | ND |
| USUDD | Underwood | WA |
| USUDF | Uneeda | WV |
| USUCO | Unicoi | TN |
| USUOM | Union | IA |
| USUNZ | Union | IL |
| USYNR | Tyner | NC |
| USTG2 | Tyngsboro | MA |
| USTYE | Tyonek | AK |
| USTYJ | Tyro | VA |
| USTYF | Tyrone | GA |
| USTYB | Tyrone | NM |
| USXNK | Tyrone | PA |
| UST9Y | Tysons Corner | VA |
| USUBY | Ubly | MI |
| USUGI | Uganik | AK |
| USUGS | Ugashik | AK |
| USUHV | Uhrichsville | OH |
| USUKI | Ukiah | CA |
| US4TP | Ulm | AR |
| USUDM | Ulm | MT |
| USUER | Ulmer | SC |
| USUL5 | Ulster Park | NY |
| US3DV | Ulupalakua | HI |
| USUSY | Ulysses | KS |
| USUZS | Ulysses | NE |
| USTWF | Twin Falls | ID |
| USTWA | Twin Hills | AK |
| USTW2 | Twin Lake | MI |
| USTVV | Twin Lakes | WI |
| US8WN | Twin Mountain | NH |
| US2RK | Twin Rocks | PA |
| USTBG | Twinsburg | OH |
| USTWI | Twisp | WA |
| USTHB | Two Harbors | MN |
| USTWR | Two Rivers | WI |
| USTYA | Ty Ty | GA |
| USZYI | Tybee Island | GA |
| USTQY | Tye | TX |
| USTE8 | Tyee | AK |
| USTYL | Tyler | AL |
| USTLX | Tyler | MN |
| USTYR | Tyler | TX |
| USTP8 | Tylersport | PA |
| USTTQ | Tylertown | MS |