South Dakota Cities
- Oacoma, SD
- Oahe Acres, SD
- Oak Lane Colony, SD
- Oelrichs, SD
- Oglala, SD
- Okaton, SD
- Okobojo, SD
- Okreek, SD
- Ola, SD
- Old Elm Spring Colony, SD
- Oldham, SD
- Olivet, SD
- Olsonville, SD
- Onaka, SD
- Onida, SD
- Opal, SD
- Oral, SD
- Ordway, SD
- Oreville, SD
- Orient, SD
- Orland, SD
- Orland Colony, SD
- Ortley, SD
- Orton, SD
- Osceola, SD
- Ottumwa, SD
- Owanka, SD
