| South Portland to Opwijk | 3,375.33 mi (5,432.06 km) |
| South Portland to Ostend | 3,317.75 mi (5,339.40 km) |
| South Portland to Oud-Heverlee | 3,398.31 mi (5,469.05 km) |
| South Portland to Oud-Turnhout | 3,398.27 mi (5,468.98 km) |
| South Portland to Oudenaarde | 3,354.80 mi (5,399.02 km) |
| South Portland to Oudenburg | 3,322.07 mi (5,346.35 km) |
| South Portland to Oupeye | 3,440.98 mi (5,537.72 km) |
| South Portland to Overijse | 3,394.26 mi (5,462.53 km) |
| South Portland to Overpelt | 3,418.22 mi (5,501.09 km) |
| South Portland to Paal | 3,413.19 mi (5,492.99 km) |
| South Portland to Peer | 3,421.93 mi (5,507.07 km) |
| South Portland to Pepinster | 3,451.84 mi (5,555.19 km) |
| South Portland to Peruwelz | 3,362.77 mi (5,411.85 km) |
| South Portland to Perwez | 3,409.87 mi (5,487.65 km) |
| South Portland to Philippeville | 3,410.51 mi (5,488.69 km) |
