| Duncan to Indianola (Iowa) | 527.55 mi (849.02 km) |
| Duncan to Indio (California) | 1,047.34 mi (1,685.53 km) |
| Duncan to Inglewood (California) | 1,165.12 mi (1,875.08 km) |
| Duncan to Inkster (Michigan) | 952.96 mi (1,533.63 km) |
| Duncan to Inver Grove Heights (Minnesota) | 755.74 mi (1,216.25 km) |
| Duncan to Inwood (New York) | 1,383.42 mi (2,226.40 km) |
| Duncan to Iona (Florida) | 1,097.86 mi (1,766.83 km) |
| Duncan to Ionia (Michigan) | 903.15 mi (1,453.48 km) |
| Duncan to Iowa City (Iowa) | 601.62 mi (968.22 km) |
| Duncan to Irmo (South Carolina) | 953.83 mi (1,535.04 km) |
| Duncan to Irondale (Alabama) | 648.04 mi (1,042.92 km) |
| Duncan to Ironton (Ohio) | 888.78 mi (1,430.35 km) |
| Duncan to Irvine (California) | 1,135.44 mi (1,827.31 km) |
| Duncan to Irving (Texas) | 128.47 mi (206.75 km) |
| Duncan to Isabela (Puerto Rico) | 2,194.93 mi (3,532.40 km) |
