| Duncan to San Luis Obispo (California) | 1,287.13 mi (2,071.43 km) |
| Duncan to San Marcos (California) | 1,107.50 mi (1,782.34 km) |
| Duncan to San Marcos (Texas) | 322.49 mi (518.99 km) |
| Duncan to San Marino (California) | 1,150.51 mi (1,851.57 km) |
| Duncan to San Mateo (California) | 1,374.40 mi (2,211.89 km) |
| Duncan to San Pablo (California) | 1,376.99 mi (2,216.05 km) |
| Duncan to San Rafael (California) | 1,386.84 mi (2,231.90 km) |
| Duncan to San Ramon (California) | 1,354.30 mi (2,179.54 km) |
| Duncan to San Tan Valley (Arizona) | 787.70 mi (1,267.69 km) |
| Duncan to Sand Springs (Oklahoma) | 149.50 mi (240.60 km) |
| Duncan to Sandusky (Ohio) | 954.21 mi (1,535.66 km) |
| Duncan to Sandy (Oregon) | 1,482.96 mi (2,386.59 km) |
| Duncan to Sandy (Utah) | 867.83 mi (1,396.64 km) |
| Duncan to Sandy Springs (Georgia) | 774.58 mi (1,246.57 km) |
| Duncan to Sanford (Florida) | 1,054.79 mi (1,697.52 km) |
