| Norristown to Orbetello | 4,286.79 mi (6,898.93 km) |
| Norristown to Oria | 4,639.44 mi (7,466.45 km) |
| Norristown to Oristano | 4,257.03 mi (6,851.03 km) |
| Norristown to Orta Nova | 4,524.07 mi (7,280.79 km) |
| Norristown to Orte | 4,337.62 mi (6,980.72 km) |
| Norristown to Ortona | 4,429.38 mi (7,128.40 km) |
| Norristown to Orvieto | 4,316.46 mi (6,946.67 km) |
| Norristown to Orzinuovi | 4,131.45 mi (6,648.93 km) |
| Norristown to Osimo | 4,349.05 mi (6,999.12 km) |
| Norristown to Ospitaletto | 4,132.37 mi (6,650.41 km) |
| Norristown to Ostuni | 4,628.25 mi (7,448.45 km) |
| Norristown to Ottaviano | 4,487.87 mi (7,222.53 km) |
| Norristown to Ovada | 4,100.64 mi (6,599.35 km) |
| Norristown to Ozieri | 4,252.26 mi (6,843.35 km) |
| Norristown to Paceco | 4,507.76 mi (7,254.54 km) |
