| Duncan to Smyrna (Delaware) | 1,271.92 mi (2,046.96 km) |
| Duncan to Smyrna (Georgia) | 766.87 mi (1,234.16 km) |
| Duncan to Smyrna (Tennessee) | 650.06 mi (1,046.17 km) |
| Duncan to Snellville (Georgia) | 796.13 mi (1,281.24 km) |
| Duncan to Snoqualmie (Washington) | 1,525.72 mi (2,455.41 km) |
| Duncan to Snyder (Texas) | 213.37 mi (343.39 km) |
| Duncan to Socastee (South Carolina) | 1,081.92 mi (1,741.19 km) |
| Duncan to Socorro (Texas) | 522.48 mi (840.85 km) |
| Duncan to Soddy-Daisy (Tennessee) | 723.57 mi (1,164.48 km) |
| Duncan to Solana Beach (California) | 1,114.02 mi (1,792.84 km) |
| Duncan to Soledad (California) | 1,320.84 mi (2,125.69 km) |
| Duncan to Solon (Ohio) | 1,012.39 mi (1,629.29 km) |
| Duncan to Somers Point (New Jersey) | 1,325.22 mi (2,132.74 km) |
| Duncan to Somerset (Kentucky) | 765.50 mi (1,231.95 km) |
| Duncan to Somerset (New Jersey) | 1,343.27 mi (2,161.78 km) |
