| Difficult Run to Security-Widefield (Colorado) | 1,467.58 mi (2,361.84 km) |
| Difficult Run to Sedalia (Missouri) | 854.44 mi (1,375.09 km) |
| Difficult Run to Sedro-Woolley (Washington) | 2,301.60 mi (3,704.07 km) |
| Difficult Run to Seguin (Texas) | 1,337.53 mi (2,152.54 km) |
| Difficult Run to Selden (New York) | 265.48 mi (427.25 km) |
| Difficult Run to Selma (Alabama) | 703.86 mi (1,132.76 km) |
| Difficult Run to Selma (California) | 2,294.49 mi (3,692.63 km) |
| Difficult Run to Selma (Texas) | 1,354.82 mi (2,180.38 km) |
| Difficult Run to Seminole (Florida) | 825.50 mi (1,328.51 km) |
| Difficult Run to Seven Hills (Ohio) | 285.51 mi (459.49 km) |
| Difficult Run to Seven Oaks (South Carolina) | 396.10 mi (637.47 km) |
| Difficult Run to Severn (Maryland) | 38.53 mi (62.00 km) |
| Difficult Run to Severna Park (Maryland) | 43.72 mi (70.36 km) |
| Difficult Run to Sevierville (Tennessee) | 399.83 mi (643.47 km) |
| Difficult Run to Seymour (Indiana) | 459.11 mi (738.86 km) |
