| Duncan to Security-Widefield (Colorado) | 475.51 mi (765.26 km) |
| Duncan to Sedalia (Missouri) | 387.67 mi (623.90 km) |
| Duncan to Sedro-Woolley (Washington) | 1,573.60 mi (2,532.46 km) |
| Duncan to Seguin (Texas) | 342.14 mi (550.62 km) |
| Duncan to Selden (New York) | 1,422.68 mi (2,289.59 km) |
| Duncan to Selma (Alabama) | 644.05 mi (1,036.49 km) |
| Duncan to Selma (California) | 1,224.78 mi (1,971.09 km) |
| Duncan to Selma (Texas) | 343.07 mi (552.12 km) |
| Duncan to Seminole (Florida) | 1,005.71 mi (1,618.53 km) |
| Duncan to Seven Hills (Ohio) | 1,001.06 mi (1,611.05 km) |
| Duncan to Seven Oaks (South Carolina) | 957.23 mi (1,540.51 km) |
| Duncan to Severn (Maryland) | 1,212.75 mi (1,951.73 km) |
| Duncan to Severna Park (Maryland) | 1,218.99 mi (1,961.78 km) |
| Duncan to Sevierville (Tennessee) | 814.83 mi (1,311.35 km) |
| Duncan to Seymour (Indiana) | 731.56 mi (1,177.34 km) |
