| Potomac to Olivares | 3,754.61 mi (6,042.46 km) |
| Potomac to Olivenza | 3,671.02 mi (5,907.93 km) |
| Potomac to Olot | 4,026.50 mi (6,480.03 km) |
| Potomac to Onate | 3,775.23 mi (6,075.65 km) |
| Potomac to Onda | 3,964.89 mi (6,380.87 km) |
| Potomac to Onteniente | 3,983.34 mi (6,410.57 km) |
| Potomac to Orihuela | 3,989.77 mi (6,420.91 km) |
| Potomac to Osuna | 3,812.13 mi (6,135.04 km) |
| Potomac to Ourense | 3,537.12 mi (5,692.44 km) |
| Potomac to Oviedo | 3,606.86 mi (5,804.69 km) |
| Potomac to Paiporta | 3,973.80 mi (6,395.22 km) |
| Potomac to Pajara | 3,629.38 mi (5,840.93 km) |
| Potomac to Palafolls | 4,054.22 mi (6,524.64 km) |
| Potomac to Palafrugell | 4,065.61 mi (6,542.97 km) |
| Potomac to Palamos | 4,066.24 mi (6,543.99 km) |
