| Duncan to Fortuna Foothills (Arizona) | 955.92 mi (1,538.40 km) |
| Duncan to Foster City (California) | 1,371.88 mi (2,207.83 km) |
| Duncan to Fostoria (Ohio) | 912.44 mi (1,468.44 km) |
| Duncan to Fountain (Colorado) | 471.72 mi (759.16 km) |
| Duncan to Fountain Hills (Arizona) | 792.84 mi (1,275.95 km) |
| Duncan to Fountain Inn (South Carolina) | 893.05 mi (1,437.22 km) |
| Duncan to Fountain Valley (California) | 1,145.19 mi (1,843.01 km) |
| Duncan to Fountainebleau (Florida) | 1,209.54 mi (1,946.57 km) |
| Duncan to Four Corners (Oregon) | 1,503.45 mi (2,419.57 km) |
| Duncan to Four Corners (Texas) | 361.58 mi (581.90 km) |
| Duncan to Four Square Mile (Colorado) | 522.62 mi (841.08 km) |
| Duncan to Fox Crossing (Wisconsin) | 836.59 mi (1,346.36 km) |
| Duncan to Fox Lake (Illinois) | 756.63 mi (1,217.68 km) |
| Duncan to Framingham (Massachusetts) | 1,523.11 mi (2,451.21 km) |
| Duncan to Franconia (Virginia) | 1,184.50 mi (1,906.27 km) |
