| North Potomac to Nuth | 3,921.92 mi (6,311.71 km) |
| North Potomac to Oegstgeest | 3,832.64 mi (6,168.04 km) |
| North Potomac to Oirschot | 3,883.15 mi (6,249.32 km) |
| North Potomac to Oisterwijk | 3,877.00 mi (6,239.43 km) |
| North Potomac to Oldebroek | 3,882.15 mi (6,247.71 km) |
| North Potomac to Oldenzaal | 3,925.96 mi (6,318.21 km) |
| North Potomac to Ommen | 3,900.56 mi (6,277.34 km) |
| North Potomac to Oosterend | 3,874.38 mi (6,235.21 km) |
| North Potomac to Oosterhout | 3,861.80 mi (6,214.97 km) |
| North Potomac to Oosterwolde | 3,883.40 mi (6,249.74 km) |
| North Potomac to Oostzaan | 3,842.77 mi (6,184.35 km) |
| North Potomac to Opmeer | 3,838.70 mi (6,177.79 km) |
| North Potomac to Oss | 3,884.80 mi (6,251.99 km) |
| North Potomac to Oud-Beijerland | 3,839.21 mi (6,178.60 km) |
| North Potomac to Oudenbosch | 3,849.91 mi (6,195.83 km) |
