| South Houston to Olivares | 4,963.19 mi (7,987.48 km) |
| South Houston to Olivenza | 4,880.85 mi (7,854.97 km) |
| South Houston to Olot | 5,235.14 mi (8,425.15 km) |
| South Houston to Onate | 4,984.98 mi (8,022.55 km) |
| South Houston to Onda | 5,176.30 mi (8,330.45 km) |
| South Houston to Onteniente | 5,194.82 mi (8,360.25 km) |
| South Houston to Orihuela | 5,200.95 mi (8,370.13 km) |
| South Houston to Osuna | 5,021.01 mi (8,080.54 km) |
| South Houston to Ourense | 4,748.57 mi (7,642.08 km) |
| South Houston to Oviedo | 4,817.37 mi (7,752.80 km) |
| South Houston to Paiporta | 5,185.32 mi (8,344.96 km) |
| South Houston to Pajara | 4,790.47 mi (7,709.52 km) |
| South Houston to Palafolls | 5,263.42 mi (8,470.66 km) |
| South Houston to Palafrugell | 5,274.27 mi (8,488.12 km) |
| South Houston to Palamos | 5,275.02 mi (8,489.32 km) |
