| Rhondda to Silver Firs (Washington) | 4,670.94 mi (7,517.14 km) |
| Rhondda to Silver Spring (Maryland) | 3,522.61 mi (5,669.09 km) |
| Rhondda to Silver Springs Shores (Florida) | 4,197.41 mi (6,755.08 km) |
| Rhondda to Silverdale (Washington) | 4,696.49 mi (7,558.28 km) |
| Rhondda to Silverton (Oregon) | 4,849.15 mi (7,803.95 km) |
| Rhondda to Simi Valley (California) | 5,333.01 mi (8,582.66 km) |
| Rhondda to Simpsonville (South Carolina) | 3,935.02 mi (6,332.80 km) |
| Rhondda to Sioux City (Iowa) | 4,119.09 mi (6,629.03 km) |
| Rhondda to Sioux Falls (South Dakota) | 4,081.51 mi (6,568.56 km) |
| Rhondda to Skokie (Illinois) | 3,814.99 mi (6,139.63 km) |
| Rhondda to Sleepy Hollow (New York) | 3,302.32 mi (5,314.58 km) |
| Rhondda to Slidell (Louisiana) | 4,461.66 mi (7,180.34 km) |
| Rhondda to Smithfield (North Carolina) | 3,736.18 mi (6,012.80 km) |
| Rhondda to Smithfield (Utah) | 4,689.28 mi (7,546.67 km) |
| Rhondda to Smithville (Missouri) | 4,201.29 mi (6,761.33 km) |
