- Old Tree Island
- Old Trower
- Old Welbourne
- Old Well Crossing
- Old Wilkins
- Olde Forge
- Olde Hunting Hills
- Olde South Estates
- Oldfields
- Oldhams
- Oldrag
- Oldtown
- Ole Orchard Estates
- Olean
- Olinger
- Olive
- Oliver
- Olivers Corner
- Olivers Estates
- Oliveville
- Olney Corner
- Olney Park
- Olympic Mobile Home Park
- Omaha
- Omega
- Onan
- Onancock
- Onemo
- Onley
- Ontario