| Code | Name | Region |
|---|---|---|
| USOAS | Oaks | PA |
| USOKU | Oakton | VA |
| USOTN | Oaktown | IN |
| USOVY | Oakville | CA |
| USOKV | Oakville | CT |
| USV6L | Oakville | KY |
| USOPV | Oakville | WA |
| USOKW | Oakwood | GA |
| USO2A | Oakwood | OH |
| USOW5 | Oakwood | TX |
| USZOV | Oakwood Village | OH |
| USOKH | Oakhurst | NJ |
| USOAK | Oakland | CA |
| USOQA | Oakland | FL |
| USOLI | Oakland | IA |
| USOUF | Oakland | IL |
| USO4K | Oakland | KY |
| USZ2G | Oakland | LA |
| USOBT | Oakland | MD |
| USOKD | Oakland | ME |
| USOQC | Oakland | MS |
| USXKB | Oakland | NJ |
| USKND | Oakland | OR |
| USOV5 | Oakland | PA |
| USDN8 | Oakland | RI |
| USOK3 | Oakland | TX |
| USZOC | Oakland City | IN |
| USO5G | Oakland Gardens | NY |
| USOXK | Oakland Mills | MD |
| USOP2 | Oakland Park, Broward | FL |
| USKAD | Oakland, Fayette | TN |
| USOFW | Oak View | CA |
| USYOB | Oakboro | NC |
| USOT2 | Oakbrook Terrace | IL |
| USOKQ | Oakdale | CA |
| USM8E | Oakdale | CT |
| USODH | Oakdale | IL |
| USODA | Oakdale | LA |
| USOKE | Oakdale | MN |
| USOQD | Oakdale | NY |
| USUXR | Oakdale | PA |
| USODD | Oakdale, Morgan | TN |
| USJYU | Oakes | ND |
| USKSE | Oakesdale | WA |
| USGKF | Oakfield | ME |
| USOK2 | Oakfield | NY |
| USKFL | Oakfield | TN |
| USOKF | Oakfield | WI |
| USK9F | Oakford | IN |
| USHK5 | Oakham | MA |