| Castro Valley to Popovo | 6,494.04 mi (10,451.15 km) |
| Castro Valley to Provadia | 6,529.29 mi (10,507.87 km) |
| Castro Valley to Radnevo | 6,553.55 mi (10,546.93 km) |
| Castro Valley to Radomir | 6,471.42 mi (10,414.74 km) |
| Castro Valley to Rakitovo | 6,532.40 mi (10,512.88 km) |
| Castro Valley to Rakovski | 6,533.19 mi (10,514.15 km) |
| Castro Valley to Razgrad | 6,488.42 mi (10,442.10 km) |
| Castro Valley to Razlog | 6,524.46 mi (10,500.10 km) |
| Castro Valley to Ruse | 6,458.50 mi (10,393.95 km) |
| Castro Valley to Samokov | 6,498.47 mi (10,458.28 km) |
| Castro Valley to Sandanski | 6,539.62 mi (10,524.51 km) |
| Castro Valley to Sevlievo | 6,490.46 mi (10,445.39 km) |
| Castro Valley to Shumen | 6,512.76 mi (10,481.28 km) |
| Castro Valley to Silistra | 6,466.77 mi (10,407.25 km) |
| Castro Valley to Sliven | 6,538.03 mi (10,521.94 km) |
