| Boulder City to Popovo | 6,444.96 mi (10,372.16 km) |
| Boulder City to Provadia | 6,485.27 mi (10,437.03 km) |
| Boulder City to Radnevo | 6,499.55 mi (10,460.01 km) |
| Boulder City to Radomir | 6,404.43 mi (10,306.94 km) |
| Boulder City to Rakitovo | 6,468.63 mi (10,410.26 km) |
| Boulder City to Rakovski | 6,474.60 mi (10,419.86 km) |
| Boulder City to Razgrad | 6,441.27 mi (10,366.22 km) |
| Boulder City to Razlog | 6,457.48 mi (10,392.30 km) |
| Boulder City to Ruse | 6,409.72 mi (10,315.44 km) |
| Boulder City to Samokov | 6,433.51 mi (10,353.73 km) |
| Boulder City to Sandanski | 6,470.66 mi (10,413.53 km) |
| Boulder City to Sevlievo | 6,435.09 mi (10,356.28 km) |
| Boulder City to Shumen | 6,466.72 mi (10,407.19 km) |
| Boulder City to Silistra | 6,424.98 mi (10,340.01 km) |
| Boulder City to Sliven | 6,487.19 mi (10,440.12 km) |
