| Boulder to Red Bank (New Jersey) | 1,637.62 mi (2,635.50 km) |
| Boulder to Red Bank (Tennessee) | 1,141.55 mi (1,837.14 km) |
| Boulder to Red Bluff (California) | 896.58 mi (1,442.90 km) |
| Boulder to Red Hill (South Carolina) | 1,506.47 mi (2,424.43 km) |
| Boulder to Red Oak (Texas) | 700.14 mi (1,126.77 km) |
| Boulder to Red Wing (Minnesota) | 717.90 mi (1,155.35 km) |
| Boulder to Redan (Georgia) | 1,240.01 mi (1,995.61 km) |
| Boulder to Redding (California) | 901.16 mi (1,450.27 km) |
| Boulder to Redland (Maryland) | 1,491.79 mi (2,400.80 km) |
| Boulder to Redlands (California) | 775.14 mi (1,247.46 km) |
| Boulder to Redmond (Oregon) | 865.22 mi (1,392.44 km) |
| Boulder to Redmond (Washington) | 989.54 mi (1,592.51 km) |
| Boulder to Redondo Beach (California) | 839.42 mi (1,350.92 km) |
| Boulder to Redwood City (California) | 929.36 mi (1,495.66 km) |
| Boulder to Reedley (California) | 804.09 mi (1,294.06 km) |
