| South Portland to Opole | 3,922.75 mi (6,313.06 km) |
| South Portland to Orzesze | 3,971.86 mi (6,392.09 km) |
| South Portland to Osowa | 3,815.71 mi (6,140.79 km) |
| South Portland to Ostroda | 3,893.10 mi (6,265.33 km) |
| South Portland to Ostroleka | 3,972.10 mi (6,392.47 km) |
| South Portland to Ostrow Mazowiecka | 3,993.50 mi (6,426.92 km) |
| South Portland to Ostrow Wielkopolski | 3,884.59 mi (6,251.65 km) |
| South Portland to Ostrowiec Swietokrzyski | 4,042.95 mi (6,506.50 km) |
| South Portland to Ostrzeszow | 3,896.90 mi (6,271.46 km) |
| South Portland to Oswiecim | 3,993.75 mi (6,427.32 km) |
| South Portland to Otwock | 3,995.21 mi (6,429.67 km) |
| South Portland to Ozarow Mazowiecki | 3,974.71 mi (6,396.67 km) |
| South Portland to Ozimek | 3,933.12 mi (6,329.74 km) |
| South Portland to Ozorkow | 3,928.04 mi (6,321.57 km) |
| South Portland to Pabianice | 3,942.77 mi (6,345.27 km) |
