- Old Point Comfort
- Olga
- Orange Avenue Junction
- Old Corral
- Ocean Roar
- O'Neil Place
- Oasis
- Old Bailey Place
- Old Hopland
- Old Ornbaun Hot Springs
- Old Red Rock Place
- Orrs Springs
- Old Hulbert Place
- Old Mammoth
- Oak Hills
- Old Hilltown
- Oak Park
- Orange
- Orosi
- Oak Knoll
- Omega
- Ophir Hill Acres
- Orleans Flat
- Oasis Mobile Home Park
- Olympic Valley
- Ophir
- Oak Haven Estates
- Oakridge Ranches
- One Hundred Palms
- Ordway