| Southborough to Montana | 1,195.11 mi (1,923.34 km) |
| Southborough to Nova Zagora | 1,347.13 mi (2,168.00 km) |
| Southborough to Novi Iskar | 1,224.69 mi (1,970.95 km) |
| Southborough to Novi Pazar | 1,363.68 mi (2,194.63 km) |
| Southborough to Omurtag | 1,340.15 mi (2,156.76 km) |
| Southborough to Panagyurishte | 1,271.10 mi (2,045.64 km) |
| Southborough to Parvomay | 1,330.00 mi (2,140.43 km) |
| Southborough to Pavlikeni | 1,288.78 mi (2,074.09 km) |
| Southborough to Pazardzhik | 1,289.62 mi (2,075.44 km) |
| Southborough to Pernik | 1,219.98 mi (1,963.37 km) |
| Southborough to Peshtera | 1,295.22 mi (2,084.45 km) |
| Southborough to Petrich | 1,278.52 mi (2,057.58 km) |
| Southborough to Pleven | 1,253.15 mi (2,016.74 km) |
| Southborough to Plovdiv | 1,308.76 mi (2,106.25 km) |
| Southborough to Pomorie | 1,411.08 mi (2,270.92 km) |
