Cities of United States starting with letter O Page 9
- Osseo (Trempealeau County)
- Oroville (Okanogan County)
- Owls Head
- Orwell
- Oak Hill (Knox County, Ohio)
- Osgood
- Orleans (Barnstable County)
- Olivet
- Ovid
- Olive Hill
- Oakwood (Vermilion County)
- Orchard Grass Hills
- Oakland (Cambria County)
- Ocean Park
- Onset
- Oakland (Lawrence County)
- Osburn
- Oak Hill (Jackson County, Ohio)
- Owingsville
- Oakland (Pottawattamie County)
- Owens Cross Roads
- Ontonagon
- Oakley (Summit County)
- Orangeville
- Oakdale (Luzerne County)
- Oblong
- Oakdale (Allegheny County)
- Oxford (Chenango County)
- Orfordville
- Ortonville (Oakland County)
- Oakland (Franklin County, Iowa)
- Okawville
- Osborne
- Oriole Beach
- Olivet (Salem County)
- Oriskany
- Oceana
- Otis
- Oakport
- Olla
- Oakland (Saint Louis County)
- Oquawka
- Onarga
- Odon
- Olivet (Hardin County, Tennessee)
- Oglethorpe
- Owenton
- Orange Grove
- Oronoco
- Oak Leaf