| Old Westbury, NY (Village) |
| Oldenburg, IN (Town) |
| Oldham, SD (Town) |
| Oldham County, KY (County) |
| Oldham County, TX (County) |
| Oldmans Township, NJ (Township) |
| Olds, IA (City) |
| Oldsmar , FL (City) |
| Oldtown, ID (City) |
| Oldtown Township, IL (Township) |
| Olean, NY (City) |
| Olean, NY (Town) |
| Olean, SD (Township) |
| Olean, MO (Town) |
| Oley Township, PA (Township) |
