| Difficult Run to Brown Deer (Wisconsin) | 626.97 mi (1,009.00 km) |
| Difficult Run to Brownsburg (Indiana) | 486.72 mi (783.30 km) |
| Difficult Run to Brownsville (Florida) | 919.24 mi (1,479.38 km) |
| Difficult Run to Brownsville (Texas) | 1,467.26 mi (2,361.32 km) |
| Difficult Run to Brownwood (Texas) | 1,312.72 mi (2,112.62 km) |
| Difficult Run to Brunswick (Georgia) | 584.43 mi (940.54 km) |
| Difficult Run to Brunswick (Ohio) | 286.59 mi (461.22 km) |
| Difficult Run to Brushy Creek (Texas) | 1,291.11 mi (2,077.84 km) |
| Difficult Run to Bryan (Texas) | 1,217.40 mi (1,959.21 km) |
| Difficult Run to Bryant (Arkansas) | 887.77 mi (1,428.73 km) |
| Difficult Run to Bryn Mawr-Skyway (Washington) | 2,303.35 mi (3,706.88 km) |
| Difficult Run to Buckeye (Arizona) | 1,991.90 mi (3,205.66 km) |
| Difficult Run to Buckhall (Virginia) | 13.42 mi (21.59 km) |
| Difficult Run to Bucyrus (Ohio) | 325.98 mi (524.61 km) |
| Difficult Run to Buda (Texas) | 1,312.94 mi (2,112.97 km) |
