| Difficult Run to Red Bank (New Jersey) | 201.11 mi (323.66 km) |
| Difficult Run to Red Bank (Tennessee) | 510.52 mi (821.61 km) |
| Difficult Run to Red Bluff (California) | 2,368.03 mi (3,810.98 km) |
| Difficult Run to Red Hill (South Carolina) | 365.92 mi (588.89 km) |
| Difficult Run to Red Oak (Texas) | 1,173.31 mi (1,888.27 km) |
| Difficult Run to Red Wing (Minnesota) | 877.11 mi (1,411.57 km) |
| Difficult Run to Redan (Georgia) | 520.51 mi (837.68 km) |
| Difficult Run to Redding (California) | 2,368.47 mi (3,811.69 km) |
| Difficult Run to Redland (Maryland) | 19.33 mi (31.11 km) |
| Difficult Run to Redlands (California) | 2,220.02 mi (3,572.77 km) |
| Difficult Run to Redmond (Oregon) | 2,268.02 mi (3,650.02 km) |
| Difficult Run to Redmond (Washington) | 2,297.20 mi (3,696.99 km) |
| Difficult Run to Redondo Beach (California) | 2,289.37 mi (3,684.39 km) |
| Difficult Run to Redwood City (California) | 2,413.79 mi (3,884.62 km) |
| Difficult Run to Reedley (California) | 2,285.07 mi (3,677.46 km) |
