| Duncan to Hutchinson (Minnesota) | 738.96 mi (1,189.24 km) |
| Duncan to Hutto (Texas) | 277.33 mi (446.32 km) |
| Duncan to Hyattsville (Maryland) | 1,197.23 mi (1,926.76 km) |
| Duncan to Hybla Valley (Virginia) | 1,188.41 mi (1,912.55 km) |
| Duncan to Idaho Falls (Idaho) | 975.52 mi (1,569.95 km) |
| Duncan to Idylwood (Virginia) | 1,183.18 mi (1,904.14 km) |
| Duncan to Ilchester (Maryland) | 1,209.77 mi (1,946.94 km) |
| Duncan to Immokalee (Florida) | 1,128.81 mi (1,816.64 km) |
| Duncan to Imperial (California) | 1,020.18 mi (1,641.83 km) |
| Duncan to Imperial Beach (California) | 1,111.98 mi (1,789.55 km) |
| Duncan to Independence (Kentucky) | 799.59 mi (1,286.82 km) |
| Duncan to Independence (Missouri) | 371.00 mi (597.06 km) |
| Duncan to Indian Trail (North Carolina) | 979.58 mi (1,576.48 km) |
| Duncan to Indiana (Pennsylvania) | 1,107.31 mi (1,782.04 km) |
| Duncan to Indianapolis (Indiana) | 741.63 mi (1,193.54 km) |
