| South Portland to Clarksdale (Mississippi) | 1,265.33 mi (2,036.35 km) |
| South Portland to Clarkston (Georgia) | 1,010.29 mi (1,625.91 km) |
| South Portland to Clarksville (Indiana) | 884.98 mi (1,424.24 km) |
| South Portland to Clarksville (Tennessee) | 1,022.02 mi (1,644.78 km) |
| South Portland to Clawson (Michigan) | 652.72 mi (1,050.44 km) |
| South Portland to Clay (Alabama) | 1,112.98 mi (1,791.17 km) |
| South Portland to Clayton (California) | 2,686.13 mi (4,322.91 km) |
| South Portland to Clayton (Missouri) | 1,095.06 mi (1,762.33 km) |
| South Portland to Clayton (North Carolina) | 700.58 mi (1,127.48 km) |
| South Portland to Clayton (Ohio) | 767.80 mi (1,235.66 km) |
| South Portland to Clearfield (Utah) | 2,115.16 mi (3,404.03 km) |
| South Portland to Clearlake (California) | 2,691.17 mi (4,331.02 km) |
| South Portland to Clearwater (Florida) | 1,284.34 mi (2,066.95 km) |
| South Portland to Cleburne (Texas) | 1,659.14 mi (2,670.13 km) |
| South Portland to Clemmons (North Carolina) | 749.04 mi (1,205.46 km) |
