| Sioux City to Popovo | 5,523.35 mi (8,888.98 km) |
| Sioux City to Provadia | 5,570.12 mi (8,964.24 km) |
| Sioux City to Radnevo | 5,570.03 mi (8,964.10 km) |
| Sioux City to Radomir | 5,458.94 mi (8,785.32 km) |
| Sioux City to Rakitovo | 5,526.36 mi (8,893.82 km) |
| Sioux City to Rakovski | 5,539.23 mi (8,914.53 km) |
| Sioux City to Razgrad | 5,522.47 mi (8,887.55 km) |
| Sioux City to Razlog | 5,511.10 mi (8,869.26 km) |
| Sioux City to Ruse | 5,489.19 mi (8,833.99 km) |
| Sioux City to Samokov | 5,490.23 mi (8,835.67 km) |
| Sioux City to Sandanski | 5,521.47 mi (8,885.94 km) |
| Sioux City to Sevlievo | 5,504.85 mi (8,859.20 km) |
| Sioux City to Shumen | 5,549.03 mi (8,930.31 km) |
| Sioux City to Silistra | 5,514.23 mi (8,874.30 km) |
| Sioux City to Sliven | 5,562.32 mi (8,951.68 km) |
