| Southborough to Silver Firs (Washington) | 4,794.21 mi (7,715.53 km) |
| Southborough to Silver Spring (Maryland) | 3,683.44 mi (5,927.93 km) |
| Southborough to Silver Springs Shores (Florida) | 4,359.24 mi (7,015.52 km) |
| Southborough to Silverdale (Washington) | 4,819.41 mi (7,756.09 km) |
| Southborough to Silverton (Oregon) | 4,974.87 mi (8,006.28 km) |
| Southborough to Simi Valley (California) | 5,473.07 mi (8,808.05 km) |
| Southborough to Simpsonville (South Carolina) | 4,096.00 mi (6,591.87 km) |
| Southborough to Sioux City (Iowa) | 4,269.82 mi (6,871.61 km) |
| Southborough to Sioux Falls (South Dakota) | 4,231.13 mi (6,809.35 km) |
| Southborough to Skokie (Illinois) | 3,970.69 mi (6,390.21 km) |
| Southborough to Sleepy Hollow (New York) | 3,463.11 mi (5,573.34 km) |
| Southborough to Slidell (Louisiana) | 4,622.12 mi (7,438.58 km) |
| Southborough to Smithfield (North Carolina) | 3,897.63 mi (6,272.64 km) |
| Southborough to Smithfield (Utah) | 4,829.12 mi (7,771.72 km) |
| Southborough to Smithville (Missouri) | 4,355.45 mi (7,009.41 km) |
