| Horn Lake to Orbetello | 5,142.49 mi (8,276.04 km) |
| Horn Lake to Oria | 5,490.90 mi (8,836.76 km) |
| Horn Lake to Oristano | 5,123.58 mi (8,245.60 km) |
| Horn Lake to Orta Nova | 5,376.17 mi (8,652.12 km) |
| Horn Lake to Orte | 5,191.43 mi (8,354.79 km) |
| Horn Lake to Ortona | 5,280.26 mi (8,497.75 km) |
| Horn Lake to Orvieto | 5,169.83 mi (8,320.03 km) |
| Horn Lake to Orzinuovi | 4,978.40 mi (8,011.96 km) |
| Horn Lake to Osimo | 5,197.42 mi (8,364.45 km) |
| Horn Lake to Ospitaletto | 4,978.47 mi (8,012.08 km) |
| Horn Lake to Ostuni | 5,479.03 mi (8,817.65 km) |
| Horn Lake to Ottaviano | 5,343.59 mi (8,599.68 km) |
| Horn Lake to Ovada | 4,952.52 mi (7,970.31 km) |
| Horn Lake to Ozieri | 5,116.55 mi (8,234.30 km) |
| Horn Lake to Paceco | 5,374.19 mi (8,648.92 km) |
