| North Potomac to Opwijk | 3,852.15 mi (6,199.44 km) |
| North Potomac to Ostend | 3,794.56 mi (6,106.75 km) |
| North Potomac to Oud-Heverlee | 3,875.14 mi (6,236.43 km) |
| North Potomac to Oud-Turnhout | 3,875.28 mi (6,236.66 km) |
| North Potomac to Oudenaarde | 3,831.52 mi (6,166.23 km) |
| North Potomac to Oudenburg | 3,798.87 mi (6,113.68 km) |
| North Potomac to Oupeye | 3,917.85 mi (6,305.18 km) |
| North Potomac to Overijse | 3,871.05 mi (6,229.85 km) |
| North Potomac to Overpelt | 3,895.23 mi (6,268.77 km) |
| North Potomac to Paal | 3,890.13 mi (6,260.56 km) |
| North Potomac to Peer | 3,898.93 mi (6,274.72 km) |
| North Potomac to Pepinster | 3,928.68 mi (6,322.59 km) |
| North Potomac to Peruwelz | 3,839.33 mi (6,178.80 km) |
| North Potomac to Perwez | 3,886.62 mi (6,254.92 km) |
| North Potomac to Philippeville | 3,887.04 mi (6,255.59 km) |
