| Code | Name | Region |
|---|---|---|
| USNIT | Nitro | WV |
| USN2W | Niwot | CO |
| USNXI | Nixa | MO |
| USNIX | Nixon | PA |
| USX8N | Nixon | TX |
| USNK3 | Noank | CT |
| USWTK | Noatak | AK |
| USNO9 | Noble | IL |
| USOBL | Noble | OK |
| US8NO | Nobleboro | ME |
| USNVB | Noblesville | IN |
| USNCL | Nichols | SC |
| USIHU | Nichols | WI |
| USNH6 | Nichols Hills | OK |
| USNS3 | Nichols, Tioga | NY |
| USNI8 | Nicholson | MS |
| USNI7 | Nicholson | PA |
| USNV3 | Nickelsville | VA |
| USNQL | Nicollet | MN |
| USNIH | Nighthawk | WA |
| USNME | Nightmute | AK |
| USNQK | Nikishka | AK |
| USNIK | Nikiski | AK |
| USNIB | Nikolai | AK |
| USIKO | Nikolski | AK |
| USNNQ | Niland | CA |
| USNIZ | Niles | CA |
| USNIL | Niles | IL |
| USNLE | Niles | MI |
| USNLS | Niles | OH |
| USN3F | Nine Mile Falls | WA |
| USUOU | Newtown | MO |
| USNWX | Newtown | OH |
| USNTW | Newtown | PA |
| USNTQ | Newtown Square | PA |
| USZNE | Newville | PA |
| USNZP | Nezperce | ID |
| USNGW | Niagara | WI |
| USIAG | Niagara Falls | NY |
| USNZU | Niangua | MO |
| USNII | Niantic | CT |
| USNIE | Niblack | AK |
| USQNX | Nibley | UT |
| USNC8 | Nicasio | CA |
| USNCQ | Nice | CA |
| USNT3 | Nicetown | PA |
| USNIV | Niceville | FL |
| USNKV | Nichen Cove | AK |
| USNCK | Nicholasville | KY |
| USICH | Nicholls | GA |