| Houston to Popovo | 6,178.38 mi (9,943.14 km) |
| Houston to Provadia | 6,230.52 mi (10,027.06 km) |
| Houston to Radnevo | 6,215.90 mi (10,003.53 km) |
| Houston to Radomir | 6,089.97 mi (9,800.86 km) |
| Houston to Rakitovo | 6,159.46 mi (9,912.69 km) |
| Houston to Rakovski | 6,179.58 mi (9,945.07 km) |
| Houston to Razgrad | 6,180.32 mi (9,946.27 km) |
| Houston to Razlog | 6,139.94 mi (9,881.28 km) |
| Houston to Ruse | 6,146.05 mi (9,891.11 km) |
| Houston to Samokov | 6,123.02 mi (9,854.05 km) |
| Houston to Sandanski | 6,146.84 mi (9,892.38 km) |
| Houston to Sevlievo | 6,151.42 mi (9,899.75 km) |
| Houston to Shumen | 6,207.40 mi (9,989.85 km) |
| Houston to Silistra | 6,180.12 mi (9,945.95 km) |
| Houston to Sliven | 6,213.16 mi (9,999.11 km) |
