| Olney Township, IL (Township) |
| Olpe, KS (City) |
| Olsburg, KS (City) |
| Olson, ND (Township) |
| Olton, TX (City) |
| Olustee, OK (Town) |
| Olympia, WA (City) |
| Olympia Fields, IL (Village) |
| Olympian Village, MO (City) |
| Olyphant, PA (Borough) |
| Oma Town, WI (Town) |
| Omaha, TX (City) |
| Omaha, AR (Town) |
| Omaha, NE (City) |
| Omaha, NE (Township) |
