| Duncan to Superior (Colorado) | 544.93 mi (876.98 km) |
| Duncan to Superior (Wisconsin) | 893.16 mi (1,437.41 km) |
| Duncan to Surprise (Arizona) | 832.60 mi (1,339.94 km) |
| Duncan to Susanville (California) | 1,304.49 mi (2,099.38 km) |
| Duncan to Sussex (Wisconsin) | 789.47 mi (1,270.54 km) |
| Duncan to Suwanee (Georgia) | 790.84 mi (1,272.73 km) |
| Duncan to Swansea (Illinois) | 520.08 mi (836.98 km) |
| Duncan to Sweetwater (Florida) | 1,207.76 mi (1,943.70 km) |
| Duncan to Sweetwater (Texas) | 202.54 mi (325.96 km) |
| Duncan to Sycamore (Illinois) | 717.84 mi (1,155.25 km) |
| Duncan to Sylacauga (Alabama) | 675.26 mi (1,086.72 km) |
| Duncan to Sylvania (Ohio) | 915.81 mi (1,473.85 km) |
| Duncan to Syosset (New York) | 1,398.57 mi (2,250.79 km) |
| Duncan to Syracuse (New York) | 1,306.31 mi (2,102.30 km) |
| Duncan to Syracuse (Utah) | 893.28 mi (1,437.60 km) |
