| Boulder to Cicero (Illinois) | 920.06 mi (1,480.70 km) |
| Boulder to Cimarron Hills (Colorado) | 85.74 mi (137.98 km) |
| Boulder to Cincinnati (Ohio) | 1,103.94 mi (1,776.62 km) |
| Boulder to Cinco Ranch (Texas) | 890.12 mi (1,432.51 km) |
| Boulder to Circleville (Ohio) | 1,181.75 mi (1,901.84 km) |
| Boulder to Citrus (California) | 806.30 mi (1,297.61 km) |
| Boulder to Citrus Heights (California) | 860.38 mi (1,384.65 km) |
| Boulder to Citrus Park (Florida) | 1,532.19 mi (2,465.83 km) |
| Boulder to Claiborne (Louisiana) | 890.78 mi (1,433.57 km) |
| Boulder to Claremont (California) | 797.69 mi (1,283.76 km) |
| Boulder to Claremont (New Hampshire) | 1,702.51 mi (2,739.92 km) |
| Boulder to Claremore (Oklahoma) | 582.72 mi (937.80 km) |
| Boulder to Clarksburg (Maryland) | 1,484.29 mi (2,388.73 km) |
| Boulder to Clarksburg (West Virginia) | 1,322.75 mi (2,128.76 km) |
| Boulder to Clarksdale (Mississippi) | 902.26 mi (1,452.04 km) |
