| Boulder to Clarkston (Georgia) | 1,233.88 mi (1,985.74 km) |
| Boulder to Clarksville (Indiana) | 1,048.18 mi (1,686.89 km) |
| Boulder to Clarksville (Tennessee) | 998.25 mi (1,606.53 km) |
| Boulder to Clawson (Michigan) | 1,157.26 mi (1,862.42 km) |
| Boulder to Clay (Alabama) | 1,116.78 mi (1,797.28 km) |
| Boulder to Clayton (California) | 905.86 mi (1,457.84 km) |
| Boulder to Clayton (Missouri) | 802.17 mi (1,290.97 km) |
| Boulder to Clayton (North Carolina) | 1,487.27 mi (2,393.53 km) |
| Boulder to Clayton (Ohio) | 1,105.79 mi (1,779.60 km) |
| Boulder to Clearfield (Utah) | 363.04 mi (584.26 km) |
| Boulder to Clearlake (California) | 928.18 mi (1,493.76 km) |
| Boulder to Clearwater (Florida) | 1,526.75 mi (2,457.07 km) |
| Boulder to Cleburne (Texas) | 686.18 mi (1,104.29 km) |
| Boulder to Clemmons (North Carolina) | 1,376.43 mi (2,215.15 km) |
| Boulder to Clemson (South Carolina) | 1,282.54 mi (2,064.04 km) |
