| Dubuque to Octeville | 4,041.96 mi (6,504.91 km) |
| Dubuque to Oignies | 4,187.59 mi (6,739.28 km) |
| Dubuque to Oissel | 4,157.30 mi (6,690.54 km) |
| Dubuque to Olivet | 4,243.26 mi (6,828.87 km) |
| Dubuque to Ollioules | 4,586.93 mi (7,381.95 km) |
| Dubuque to Olonne-sur-Mer | 4,146.58 mi (6,673.28 km) |
| Dubuque to Oloron-Sainte-Marie | 4,319.51 mi (6,951.58 km) |
| Dubuque to Onet Village | 4,405.74 mi (7,090.36 km) |
| Dubuque to Onnaing | 4,213.04 mi (6,780.24 km) |
| Dubuque to Orange | 4,504.19 mi (7,248.79 km) |
| Dubuque to Orchies | 4,196.69 mi (6,753.92 km) |
| Dubuque to Orleans | 4,242.14 mi (6,827.06 km) |
| Dubuque to Orly | 4,229.20 mi (6,806.25 km) |
| Dubuque to Ormesson-sur-Marne | 4,233.20 mi (6,812.67 km) |
| Dubuque to Orsay | 4,223.05 mi (6,796.35 km) |
