Railroad Archives Online
| Places term | Scope note | Archival description count | Authority record count |
|---|---|---|---|
| Ononadaga Mine (Minn.) | 0 | 0 | |
| Onion Creek (Wash.) | 2 | 0 | |
| O'Neill (Neb.) | 5 | 0 | |
| Oneida (Iowa) | 0 | 0 | |
| Onega (Minn.) | 30 | 0 | |
| Onalaska (Wis.) | 0 | 0 | |
| Omro (Wis.) | 0 | 0 | |
| Omill (Idaho) | 0 | 0 | |
| Omera (Minn.) | 0 | 0 | |
| Omemee (N.D.) | 40 | 0 |