| Owings Mills to Oberkirch | 4,046.82 mi (6,512.73 km) |
| Owings Mills to Obernburg am Main | 4,051.00 mi (6,519.45 km) |
| Owings Mills to Obernkirchen | 3,979.71 mi (6,404.73 km) |
| Owings Mills to Oberschleissheim | 4,198.41 mi (6,756.69 km) |
| Owings Mills to Oberstdorf | 4,172.37 mi (6,714.78 km) |
| Owings Mills to Obertraubling | 4,199.66 mi (6,758.69 km) |
| Owings Mills to Obertshausen | 4,031.91 mi (6,488.74 km) |
| Owings Mills to Oberursel | 4,017.63 mi (6,465.75 km) |
| Owings Mills to Ochsenfurt | 4,093.90 mi (6,588.50 km) |
| Owings Mills to Ochsenhausen | 4,137.78 mi (6,659.11 km) |
| Owings Mills to Ochtrup | 3,906.61 mi (6,287.08 km) |
| Owings Mills to Odenthal | 3,935.70 mi (6,333.90 km) |
| Owings Mills to Oelde | 3,954.27 mi (6,363.78 km) |
| Owings Mills to Oelsnitz | 4,153.55 mi (6,684.50 km) |
| Owings Mills to Oer-Erkenschwick | 3,924.27 mi (6,315.50 km) |
