Collection place
- Oakville area, Napa Valley, Napa County1 objects
- Oaxaca, Mexico26 objects
- Oceania267 objects
- Oceanside, San Diego County, California1 objects
- Okavango delta, Botswana1 objects
- Okayama Prefecture, San'yo region Chugoku region1 objects
- Okinawa Prefecture, Kyushu, Japan6 objects
- Old Cariboo, Plumas County, California2 objects
- Old Town, Penobscot County, Maine1 objects
- Olympic Peninsula, Western Washington32 objects
- Onondaga Castle, Onondaga Reservation, Onondaga County1 objects
- Onondaga County, New York1 objects
- Onondaga Reservation, Onondaga County, New York1 objects
- Ontario, Canada3 objects
- Orange County, California1 objects
- Oregon449 objects
- Orleans area, Humboldt County, California14 objects
- Orleans, Humboldt County, California12 objects
- Oromia Region, Ethiopia10 objects
- Orona Atoll, Phoenix Islands, Kiribati4 objects