| Houston to Montalegre | 4,767.40 mi (7,672.39 km) |
| Houston to Montemor-o-Novo | 4,829.44 mi (7,772.24 km) |
| Houston to Montemor-o-Velho | 4,766.73 mi (7,671.31 km) |
| Houston to Montijo | 4,794.50 mi (7,715.99 km) |
| Houston to Mortagua | 4,781.85 mi (7,695.64 km) |
| Houston to Moura | 4,881.58 mi (7,856.15 km) |
| Houston to Murtosa | 4,754.65 mi (7,651.88 km) |
| Houston to Nazare | 4,762.43 mi (7,664.40 km) |
| Houston to Nelas | 4,798.35 mi (7,722.20 km) |
| Houston to Obidos | 4,764.15 mi (7,667.16 km) |
| Houston to Odemira | 4,836.99 mi (7,784.38 km) |
| Houston to Odivelas | 4,777.75 mi (7,689.04 km) |
| Houston to Oeiras | 4,773.68 mi (7,682.49 km) |
| Houston to Olhao | 4,892.13 mi (7,873.13 km) |
| Houston to Oliveira de Azemeis | 4,759.62 mi (7,659.87 km) |
