| Mountlake Terrace to Smolyan | 5,940.53 mi (9,560.36 km) |
| Mountlake Terrace to Sofia | 5,842.73 mi (9,402.97 km) |
| Mountlake Terrace to Sopot | 5,872.90 mi (9,451.52 km) |
| Mountlake Terrace to Sozopol | 5,940.82 mi (9,560.83 km) |
| Mountlake Terrace to Sredets | 5,936.50 mi (9,553.87 km) |
| Mountlake Terrace to Stamboliyski | 5,902.04 mi (9,498.41 km) |
| Mountlake Terrace to Stara Zagora | 5,903.45 mi (9,500.69 km) |
| Mountlake Terrace to Svilengrad | 5,956.51 mi (9,586.08 km) |
| Mountlake Terrace to Svishtov | 5,821.70 mi (9,369.13 km) |
| Mountlake Terrace to Targovishte | 5,867.35 mi (9,442.58 km) |
| Mountlake Terrace to Teteven | 5,846.73 mi (9,409.40 km) |
| Mountlake Terrace to Troyan | 5,857.29 mi (9,426.39 km) |
| Mountlake Terrace to Tryavna | 5,872.75 mi (9,451.28 km) |
| Mountlake Terrace to Tutrakan | 5,816.12 mi (9,360.14 km) |
| Mountlake Terrace to Varna | 5,892.44 mi (9,482.97 km) |
