| Difficult Run to Badger (Alaska) | 3,251.02 mi (5,232.01 km) |
| Difficult Run to Bailey's Crossroads (Virginia) | 12.23 mi (19.69 km) |
| Difficult Run to Bainbridge (Georgia) | 687.15 mi (1,105.86 km) |
| Difficult Run to Bainbridge Island (Washington) | 2,317.10 mi (3,729.02 km) |
| Difficult Run to Baker (Louisiana) | 970.35 mi (1,561.63 km) |
| Difficult Run to Bakersfield (California) | 2,289.66 mi (3,684.85 km) |
| Difficult Run to Balch Springs (Texas) | 1,158.16 mi (1,863.89 km) |
| Difficult Run to Baldwin (New York) | 232.44 mi (374.08 km) |
| Difficult Run to Baldwin (Pennsylvania) | 172.36 mi (277.38 km) |
| Difficult Run to Baldwin Park (California) | 2,262.21 mi (3,640.67 km) |
| Difficult Run to Ballenger Creek (Maryland) | 33.34 mi (53.65 km) |
| Difficult Run to Ballwin (Missouri) | 711.15 mi (1,144.48 km) |
| Difficult Run to Baltimore (Maryland) | 48.17 mi (77.53 km) |
| Difficult Run to Bangor (Maine) | 600.83 mi (966.94 km) |
| Difficult Run to Banning (California) | 2,207.97 mi (3,553.38 km) |
