| Boston to Olivares | 1,114.54 mi (1,793.68 km) |
| Boston to Olivenza | 1,043.15 mi (1,678.79 km) |
| Boston to Olot | 754.64 mi (1,214.48 km) |
| Boston to Onate | 695.60 mi (1,119.46 km) |
| Boston to Onda | 899.08 mi (1,446.93 km) |
| Boston to Onteniente | 978.19 mi (1,574.25 km) |
| Boston to Orihuela | 1,029.64 mi (1,657.05 km) |
| Boston to Osuna | 1,114.71 mi (1,793.96 km) |
| Boston to Ourense | 819.47 mi (1,318.80 km) |
| Boston to Oviedo | 715.84 mi (1,152.03 km) |
| Boston to Paiporta | 936.14 mi (1,506.57 km) |
| Boston to Pajara | 1,846.80 mi (2,972.14 km) |
| Boston to Palafolls | 791.64 mi (1,274.03 km) |
| Boston to Palafrugell | 778.09 mi (1,252.22 km) |
| Boston to Palamos | 782.67 mi (1,259.58 km) |
