Railroad Archives Online
| Places term | Scope note | Archival description count | Authority record count |
|---|---|---|---|
| Opheim {Mont.) | 1 | 0 | |
| Opheim (Mont.) | 31 | 0 | |
| Opheim Line Jct. | 0 | 0 | |
| Opal City (Or.) | 105 | 0 | |
| Oolitic (Ind.) | 0 | 0 | |
| Ontonagon (Mich.) | 0 | 0 | |
| Ontarioville (Ill.) | 0 | 0 | |
| Ontario (5) | 0 | 0 | |
| Onslow (Wash.) | 2 | 0 | |
| Onondaga Mine (Minn.) | 11 | 0 |