| Willoughby to Siloam Springs (Arkansas) | 798.84 mi (1,285.61 km) |
| Willoughby to Silver Firs (Washington) | 2,019.93 mi (3,250.77 km) |
| Willoughby to Silver Spring (Maryland) | 294.50 mi (473.95 km) |
| Willoughby to Silver Springs Shores (Florida) | 866.63 mi (1,394.71 km) |
| Willoughby to Silverdale (Washington) | 2,045.46 mi (3,291.85 km) |
| Willoughby to Silverton (Oregon) | 2,069.68 mi (3,330.83 km) |
| Willoughby to Simi Valley (California) | 2,079.77 mi (3,347.07 km) |
| Willoughby to Simpsonville (South Carolina) | 480.14 mi (772.71 km) |
| Willoughby to Sioux City (Iowa) | 769.63 mi (1,238.60 km) |
| Willoughby to Sioux Falls (South Dakota) | 789.12 mi (1,269.97 km) |
| Willoughby to Skokie (Illinois) | 326.95 mi (526.18 km) |
| Willoughby to Sleepy Hollow (New York) | 392.50 mi (631.66 km) |
| Willoughby to Slidell (Louisiana) | 912.73 mi (1,468.90 km) |
| Willoughby to Smithfield (North Carolina) | 454.71 mi (731.78 km) |
| Willoughby to Smithfield (Utah) | 1,559.99 mi (2,510.56 km) |
