| Duncan to Altus (Oklahoma) | 79.15 mi (127.38 km) |
| Duncan to Alum Rock (California) | 1,347.36 mi (2,168.37 km) |
| Duncan to Alvin (Texas) | 387.92 mi (624.30 km) |
| Duncan to Amarillo (Texas) | 226.25 mi (364.11 km) |
| Duncan to Amelia (Ohio) | 817.93 mi (1,316.34 km) |
| Duncan to American Canyon (California) | 1,373.13 mi (2,209.83 km) |
| Duncan to American Fork (Utah) | 859.78 mi (1,383.69 km) |
| Duncan to Americus (Georgia) | 808.37 mi (1,300.94 km) |
| Duncan to Ames (Iowa) | 567.09 mi (912.65 km) |
| Duncan to Amherst (Ohio) | 975.18 mi (1,569.41 km) |
| Duncan to Ammon (Idaho) | 971.75 mi (1,563.88 km) |
| Duncan to Amsterdam (New York) | 1,398.09 mi (2,250.01 km) |
| Duncan to Anacortes (Washington) | 1,588.80 mi (2,556.93 km) |
| Duncan to Anaheim (California) | 1,138.57 mi (1,832.36 km) |
| Duncan to Anchorage (Alaska) | 2,886.55 mi (4,645.46 km) |
