| Boulder to Security-Widefield (Colorado) | 92.72 mi (149.22 km) |
| Boulder to Sedalia (Missouri) | 647.91 mi (1,042.71 km) |
| Boulder to Sedro-Woolley (Washington) | 1,020.82 mi (1,642.85 km) |
| Boulder to Seguin (Texas) | 830.34 mi (1,336.30 km) |
| Boulder to Selden (New York) | 1,684.79 mi (2,711.41 km) |
| Boulder to Selma (Alabama) | 1,140.45 mi (1,835.38 km) |
| Boulder to Selma (California) | 813.42 mi (1,309.07 km) |
| Boulder to Selma (Texas) | 820.98 mi (1,321.24 km) |
| Boulder to Seminole (Florida) | 1,531.62 mi (2,464.90 km) |
| Boulder to Seven Hills (Ohio) | 1,234.78 mi (1,987.19 km) |
| Boulder to Seven Oaks (South Carolina) | 1,387.36 mi (2,232.74 km) |
| Boulder to Severn (Maryland) | 1,515.44 mi (2,438.87 km) |
| Boulder to Severna Park (Maryland) | 1,522.78 mi (2,450.68 km) |
| Boulder to Sevierville (Tennessee) | 1,212.13 mi (1,950.74 km) |
| Boulder to Seymour (Indiana) | 1,033.07 mi (1,662.57 km) |
