| Boston to Smolyan | 1,389.60 mi (2,236.34 km) |
| Boston to Sofia | 1,285.77 mi (2,069.24 km) |
| Boston to Sopot | 1,342.38 mi (2,160.36 km) |
| Boston to Sozopol | 1,467.82 mi (2,362.24 km) |
| Boston to Sredets | 1,451.09 mi (2,335.30 km) |
| Boston to Stamboliyski | 1,357.63 mi (2,184.90 km) |
| Boston to Stara Zagora | 1,386.92 mi (2,232.03 km) |
| Boston to Svilengrad | 1,438.42 mi (2,314.92 km) |
| Boston to Svishtov | 1,323.35 mi (2,129.73 km) |
| Boston to Targovishte | 1,387.65 mi (2,233.21 km) |
| Boston to Teteven | 1,311.78 mi (2,111.11 km) |
| Boston to Troyan | 1,330.65 mi (2,141.47 km) |
| Boston to Tryavna | 1,361.78 mi (2,191.58 km) |
| Boston to Tutrakan | 1,355.43 mi (2,181.36 km) |
| Boston to Varna | 1,442.01 mi (2,320.68 km) |
