| Potomac to Oberkirch | 4,080.94 mi (6,567.64 km) |
| Potomac to Obernburg am Main | 4,085.32 mi (6,574.69 km) |
| Potomac to Obernkirchen | 4,014.29 mi (6,460.38 km) |
| Potomac to Oberschleissheim | 4,232.64 mi (6,811.78 km) |
| Potomac to Oberstdorf | 4,206.43 mi (6,769.60 km) |
| Potomac to Obertraubling | 4,234.00 mi (6,813.96 km) |
| Potomac to Obertshausen | 4,066.25 mi (6,544.00 km) |
| Potomac to Oberursel | 4,051.98 mi (6,521.03 km) |
| Potomac to Ochsenfurt | 4,128.24 mi (6,643.76 km) |
| Potomac to Ochsenhausen | 4,171.91 mi (6,714.05 km) |
| Potomac to Ochtrup | 3,941.13 mi (6,342.64 km) |
| Potomac to Odenthal | 3,970.10 mi (6,389.25 km) |
| Potomac to Oelde | 3,988.78 mi (6,419.32 km) |
| Potomac to Oelsnitz | 4,188.05 mi (6,740.01 km) |
| Potomac to Oer-Erkenschwick | 3,958.73 mi (6,370.97 km) |
