| Gaithersburg to Oliveira de Frades | 3,560.35 mi (5,729.83 km) |
| Gaithersburg to Oliveira do Bairro | 3,550.23 mi (5,713.55 km) |
| Gaithersburg to Oliveira do Hospital | 3,585.38 mi (5,770.10 km) |
| Gaithersburg to Ourem | 3,570.02 mi (5,745.40 km) |
| Gaithersburg to Ovar | 3,534.64 mi (5,688.45 km) |
| Gaithersburg to Pacos de Ferreira | 3,535.60 mi (5,690.00 km) |
| Gaithersburg to Palmela | 3,583.17 mi (5,766.56 km) |
| Gaithersburg to Paredes | 3,540.53 mi (5,697.93 km) |
| Gaithersburg to Paredes de Coura | 3,511.42 mi (5,651.08 km) |
| Gaithersburg to Penacova | 3,567.27 mi (5,740.96 km) |
| Gaithersburg to Penafiel | 3,542.75 mi (5,701.51 km) |
| Gaithersburg to Peniche | 3,538.79 mi (5,695.14 km) |
| Gaithersburg to Peso da Regua | 3,568.27 mi (5,742.58 km) |
| Gaithersburg to Pinhal Novo | 3,580.70 mi (5,762.59 km) |
| Gaithersburg to Pinhel | 3,612.57 mi (5,813.87 km) |
