| Southborough to Carson (California) | 5,481.83 mi (8,822.16 km) |
| Southborough to Carson City (Nevada) | 5,224.21 mi (8,407.56 km) |
| Southborough to Carteret (New Jersey) | 3,499.54 mi (5,631.96 km) |
| Southborough to Cartersville (Georgia) | 4,227.23 mi (6,803.08 km) |
| Southborough to Carthage (Missouri) | 4,457.00 mi (7,172.85 km) |
| Southborough to Cary (Illinois) | 3,981.90 mi (6,408.25 km) |
| Southborough to Cary (North Carolina) | 3,904.60 mi (6,283.84 km) |
| Southborough to Casa de Oro-Mount Helix (California) | 5,501.18 mi (8,853.29 km) |
| Southborough to Casa Grande (Arizona) | 5,317.22 mi (8,557.24 km) |
| Southborough to Casas Adobes (Arizona) | 5,322.33 mi (8,565.46 km) |
| Southborough to Cascades (Virginia) | 3,696.50 mi (5,948.95 km) |
| Southborough to Casper (Wyoming) | 4,596.34 mi (7,397.10 km) |
| Southborough to Casselberry (Florida) | 4,352.34 mi (7,004.42 km) |
| Southborough to Castaic (California) | 5,456.98 mi (8,782.16 km) |
| Southborough to Castle Pines (Colorado) | 4,723.86 mi (7,602.32 km) |
