- Ontario Beach
- Ontario Center
- Ontario on the Lake
- Onteo Beach
- Onteora Park
- Oot Park
- Oppenheim
- Oramel
- Oran
- Orange Lake Mobile Home Park
- Orangeburg, Saratoga
- Orangeport
- Orangeville Center
- Orchard Grove Village Park
- Orchard Knoll
- Orchard Mobile Home Park
- Orchard Park
- Orchard Terrace
- Orchard Village
- Oregon
- Oregon
- Oregon
- Orient Island
- Orient Point
- Orienta
- Oriental Park
- Orlando
- Orleans
- Orleans Four Corners
- Orrs Mill