| Merthyr Tudful to Blue Springs (Missouri) | 4,205.71 mi (6,768.43 km) |
| Merthyr Tudful to Bluffdale (Utah) | 4,761.44 mi (7,662.79 km) |
| Merthyr Tudful to Bluffton (Indiana) | 3,771.69 mi (6,069.95 km) |
| Merthyr Tudful to Bluffton (South Carolina) | 4,000.02 mi (6,437.41 km) |
| Merthyr Tudful to Blythe (California) | 5,226.31 mi (8,410.93 km) |
| Merthyr Tudful to Blytheville (Arkansas) | 4,185.84 mi (6,736.46 km) |
| Merthyr Tudful to Boca Raton (Florida) | 4,253.67 mi (6,845.62 km) |
| Merthyr Tudful to Boerne (Texas) | 4,845.27 mi (7,797.71 km) |
| Merthyr Tudful to Bogalusa (Louisiana) | 4,439.15 mi (7,144.12 km) |
| Merthyr Tudful to Boiling Springs (South Carolina) | 3,907.74 mi (6,288.90 km) |
| Merthyr Tudful to Boise (Idaho) | 4,729.15 mi (7,610.82 km) |
| Merthyr Tudful to Bolingbrook (Illinois) | 3,842.48 mi (6,183.87 km) |
| Merthyr Tudful to Bolivar (Missouri) | 4,241.67 mi (6,826.31 km) |
| Merthyr Tudful to Bon Air (Virginia) | 3,611.19 mi (5,811.66 km) |
| Merthyr Tudful to Bonham (Texas) | 4,549.90 mi (7,322.35 km) |
