| Code | Name | Region |
|---|---|---|
| USOHU | Oakhurst | CA |
| USODW | Oak Harbor | WA |
| USOQH | Oak Hill | FL |
| USFKH | Oak Hill | NY |
| USOAH | Oak Hill | OH |
| USKHJ | Oak Hill | WV |
| USOAV | Oak Hill, Fairfax | VA |
| USOHL | Oak Hill, Pittsylvania | VA |
| USOJH | Oak Hills | CA |
| USOAI | Oak Island | NC |
| USOKI | Oak Island | NJ |
| USOKL | Oak Lawn | IL |
| USQ8P | Oak Park | CA |
| USQOP | Oak Park | IL |
| USOPJ | Oak Park Heights | MN |
| USOPC | Oak Park, Oakland | MI |
| USKOI | Oak Point | TX |
| USOR4 | Oak Ridge | NC |
| USORE | Oak Ridge | NJ |
| USOKR | Oak Ridge | TN |
| USO3A | Oak Ridge North | TX |
| USNFU | Nursery | TX |
| USNUT | Nutley | NJ |
| USVGK | Nutting Lake | MA |
| USZNC | Nyac | AK |
| USNYX | Nyack | NY |
| USYEZ | Nye | MT |
| USNSZ | Nyssa | OR |
| USQA8 | Oak | NE |
| USOKP | Oak | PA |
| USOB2 | Oak Bluffs | MA |
| USQHO | Oak Brook | IL |
| USOCK | Oak Creek | CO |
| USOAC | Oak Creek | WI |
| USOFR | Oak Forest | IL |
| USQOG | Oak Grove | IL |
| USOGK | Oak Grove | LA |
| USIKG | Oak Grove | MO |
| USOGR | Oak Grove | OR |
| USAKJ | Oak Grove | VA |
| USOHO | Oak Harbor | OH |
| USNT4 | Nottingham | NH |
| USNHG | Nottingham | PA |
| USNT9 | Notus | ID |
| USXJP | Nova | OH |
| USNOT | Novato | CA |
| USOVV | Novelty | MO |
| USZGW | Novelty | OH |
| USNOV | Novi | MI |
| USNTK | Nowata | OK |