| Duncan to McKeesport (Pennsylvania) | 1,067.13 mi (1,717.39 km) |
| Duncan to McKinleyville (California) | 1,489.98 mi (2,397.89 km) |
| Duncan to McKinney (Texas) | 117.22 mi (188.65 km) |
| Duncan to McLean (Virginia) | 1,184.32 mi (1,905.98 km) |
| Duncan to McMinnville (Oregon) | 1,520.14 mi (2,446.43 km) |
| Duncan to McMinnville (Tennessee) | 690.26 mi (1,110.87 km) |
| Duncan to McNair (Virginia) | 1,172.86 mi (1,887.54 km) |
| Duncan to McPherson (Kansas) | 265.07 mi (426.58 km) |
| Duncan to Mead Valley (California) | 1,106.11 mi (1,780.11 km) |
| Duncan to Meadow Woods (Florida) | 1,064.13 mi (1,712.56 km) |
| Duncan to Meadowbrook (Virginia) | 1,158.09 mi (1,863.76 km) |
| Duncan to Meadville (Pennsylvania) | 1,081.20 mi (1,740.03 km) |
| Duncan to Mebane (North Carolina) | 1,055.15 mi (1,698.10 km) |
| Duncan to Mechanicsville (Virginia) | 1,165.49 mi (1,875.67 km) |
| Duncan to Medford (Massachusetts) | 1,541.13 mi (2,480.21 km) |
