Towns
| State | City/Town | Town Title |
|---|---|---|
| Pennsylvania | Oakmont | Oakmont, PA |
| Pennsylvania | Oaks | Oaks, PA |
| Pennsylvania | Ohiopyle | Ohiopyle, PA |
| Pennsylvania | Oil City | Oil City, PA |
| Pennsylvania | Olanta | Olanta, PA |
| Pennsylvania | Old Forge | Old Forge, PA |
| Pennsylvania | Old Zionsville | Old Zionsville, PA |
| Pennsylvania | Oley | Oley, PA |
| Pennsylvania | Oliveburg | Oliveburg, PA |
| Pennsylvania | Oliver | Oliver, PA |
| Pennsylvania | Olyphant | Olyphant, PA |
| Pennsylvania | Oneida | Oneida, PA |
| Pennsylvania | Ono | Ono, PA |
| Pennsylvania | Orangeville | Orangeville, PA |
| Pennsylvania | Orbisonia | Orbisonia, PA |
| Pennsylvania | Orefield | Orefield, PA |
| Pennsylvania | Oreland | Oreland, PA |
| Pennsylvania | Orrstown | Orrstown, PA |
| Pennsylvania | Orrtanna | Orrtanna, PA |
| Pennsylvania | Orson | Orson, PA |
| Pennsylvania | Orwigsburg | Orwigsburg, PA |
| Pennsylvania | Osceola | Osceola, PA |
| Pennsylvania | Osceola Mills | Osceola Mills, PA |
| Pennsylvania | Osterburg | Osterburg, PA |
| Pennsylvania | Ottsville | Ottsville, PA |