| Duluth to Orbetello | 4,696.65 mi (7,558.53 km) |
| Duluth to Oria | 5,024.36 mi (8,085.92 km) |
| Duluth to Oristano | 4,719.50 mi (7,595.30 km) |
| Duluth to Orta Nova | 4,913.94 mi (7,908.23 km) |
| Duluth to Orte | 4,738.45 mi (7,625.81 km) |
| Duluth to Ortona | 4,816.40 mi (7,751.24 km) |
| Duluth to Orvieto | 4,715.95 mi (7,589.60 km) |
| Duluth to Orzinuovi | 4,510.07 mi (7,258.26 km) |
| Duluth to Osimo | 4,728.15 mi (7,609.22 km) |
| Duluth to Ospitaletto | 4,507.82 mi (7,254.64 km) |
| Duluth to Ostuni | 5,010.70 mi (8,063.94 km) |
| Duluth to Ottaviano | 4,893.47 mi (7,875.28 km) |
| Duluth to Ovada | 4,498.98 mi (7,240.41 km) |
| Duluth to Ozieri | 4,702.87 mi (7,568.54 km) |
| Duluth to Paceco | 4,964.08 mi (7,988.92 km) |
