Place
- Oaxaca1
- Oceania1
- Ohio--Fairfield County1
- Ohio--Montgomery County1
- Ohio--Newark1
- Oklahoma--Ellis County1
- Oklahoma--Johnston County1
- Oklahoma--Kiowa County1
- Oklahoma--McCurtain County1
- Oklahoma--Okfuskee County1
- Oklahoma--Okmulgee County1
- Oklahoma--Osage County1
- Oklahoma--Pushmataha County1
- Oklahoma--Roger Mills County1
- Oklahoma--Woods County1
- Oklahoma--Woodward County1
- Olivia1
- Oman1
- Ontario, Canada1
- Ontario--Toronto1