| South Portland to Olivares | 3,311.83 mi (5,329.88 km) |
| South Portland to Olivenza | 3,224.96 mi (5,190.07 km) |
| South Portland to Olot | 3,560.25 mi (5,729.67 km) |
| South Portland to Onate | 3,310.99 mi (5,328.53 km) |
| South Portland to Onda | 3,506.55 mi (5,643.24 km) |
| South Portland to Onteniente | 3,528.57 mi (5,678.69 km) |
| South Portland to Orihuela | 3,537.59 mi (5,693.20 km) |
| South Portland to Osuna | 3,368.46 mi (5,421.02 km) |
| South Portland to Ourense | 3,079.61 mi (4,956.15 km) |
| South Portland to Oviedo | 3,144.57 mi (5,060.70 km) |
| South Portland to Paiporta | 3,517.10 mi (5,660.22 km) |
| South Portland to Pajara | 3,246.80 mi (5,225.21 km) |
| South Portland to Palafolls | 3,588.86 mi (5,775.71 km) |
| South Portland to Palafrugell | 3,599.38 mi (5,792.64 km) |
| South Portland to Palamos | 3,600.19 mi (5,793.94 km) |
