| Boulder to Carson (California) | 834.51 mi (1,343.01 km) |
| Boulder to Carson City (Nevada) | 773.32 mi (1,244.53 km) |
| Boulder to Carteret (New Jersey) | 1,626.65 mi (2,617.85 km) |
| Boulder to Cartersville (Georgia) | 1,194.32 mi (1,922.07 km) |
| Boulder to Carthage (Missouri) | 622.31 mi (1,001.51 km) |
| Boulder to Cary (Illinois) | 896.28 mi (1,442.43 km) |
| Boulder to Cary (North Carolina) | 1,464.89 mi (2,357.50 km) |
| Boulder to Casa de Oro-Mount Helix (California) | 821.14 mi (1,321.50 km) |
| Boulder to Casa Grande (Arizona) | 610.10 mi (981.86 km) |
| Boulder to Casas Adobes (Arizona) | 620.05 mi (997.88 km) |
| Boulder to Cascades (Virginia) | 1,480.32 mi (2,382.34 km) |
| Boulder to Casper (Wyoming) | 202.36 mi (325.67 km) |
| Boulder to Casselberry (Florida) | 1,567.38 mi (2,522.45 km) |
| Boulder to Castaic (California) | 828.26 mi (1,332.96 km) |
| Boulder to Castle Pines (Colorado) | 43.83 mi (70.53 km) |
