| Houston to Olivares | 4,966.47 mi (7,992.76 km) |
| Houston to Olivenza | 4,883.93 mi (7,859.93 km) |
| Houston to Olot | 5,236.78 mi (8,427.78 km) |
| Houston to Onate | 4,986.80 mi (8,025.48 km) |
| Houston to Onda | 5,178.61 mi (8,334.17 km) |
| Houston to Onteniente | 5,197.38 mi (8,364.38 km) |
| Houston to Orihuela | 5,203.70 mi (8,374.55 km) |
| Houston to Osuna | 5,024.25 mi (8,085.76 km) |
| Houston to Ourense | 4,750.91 mi (7,645.85 km) |
| Houston to Oviedo | 4,819.35 mi (7,756.00 km) |
| Houston to Paiporta | 5,187.75 mi (8,348.87 km) |
| Houston to Pajara | 4,796.21 mi (7,718.75 km) |
| Houston to Palafolls | 5,265.14 mi (8,473.43 km) |
| Houston to Palafrugell | 5,275.91 mi (8,490.75 km) |
| Houston to Palamos | 5,276.67 mi (8,491.98 km) |
