| Duncan to Cibolo (Texas) | 344.32 mi (554.14 km) |
| Duncan to Cicero (Illinois) | 746.79 mi (1,201.84 km) |
| Duncan to Cimarron Hills (Colorado) | 479.37 mi (771.47 km) |
| Duncan to Cincinnati (Ohio) | 806.00 mi (1,297.12 km) |
| Duncan to Cinco Ranch (Texas) | 354.98 mi (571.28 km) |
| Duncan to Circleville (Ohio) | 895.85 mi (1,441.74 km) |
| Duncan to Citrus (California) | 1,137.85 mi (1,831.19 km) |
| Duncan to Citrus Heights (California) | 1,323.34 mi (2,129.71 km) |
| Duncan to Citrus Park (Florida) | 1,009.25 mi (1,624.22 km) |
| Duncan to Claiborne (Louisiana) | 357.41 mi (575.19 km) |
| Duncan to Claremont (California) | 1,127.90 mi (1,815.18 km) |
| Duncan to Claremont (New Hampshire) | 1,496.22 mi (2,407.94 km) |
| Duncan to Claremore (Oklahoma) | 178.77 mi (287.71 km) |
| Duncan to Clarksburg (Maryland) | 1,183.54 mi (1,904.73 km) |
| Duncan to Clarksburg (West Virginia) | 1,023.96 mi (1,647.90 km) |
