- Oak Grove School, Williamston, Anderson County, South Carolina, United States1
- Oak Grove, Lexington County, South Carolina, United States2
- Oak Ridge (Tenn.)1
- Oakland (Calif.)1
- Oconee County (S.C.)15
- Ohio1
- Okinawa6
- Okinawa (Japan)2
- Oklahoma City, Oklahoma County, Oklahoma, United States1
- Old Orchard Beach (Me.)1
- Omaha (Neb.)1
- Orange (N.J.)2
- Orange Parish (S.C.)1
- Orangeburg (S.C.)5
- Orangeburg County (S.C.)33
- Orangeburg County (S.C.); Aiken County (S.C.)1
- Orangeburg County (SC)3
- Orangeburg, SC1
- Orangeburg, South Carolina2
- Orangeburg, South Carolina 1