| Duncan to Ridgeland (Mississippi) | 471.09 mi (758.14 km) |
| Duncan to Ridgewood (New Jersey) | 1,369.37 mi (2,203.79 km) |
| Duncan to Rifle (Colorado) | 643.09 mi (1,034.95 km) |
| Duncan to Rincon (Georgia) | 973.57 mi (1,566.81 km) |
| Duncan to Ringwood (New Jersey) | 1,362.81 mi (2,193.23 km) |
| Duncan to Río Grande (Puerto Rico) | 2,262.37 mi (3,640.93 km) |
| Duncan to Rio Grande City (Texas) | 566.33 mi (911.43 km) |
| Duncan to Rio Linda (California) | 1,331.55 mi (2,142.92 km) |
| Duncan to Rio Rancho (New Mexico) | 499.76 mi (804.29 km) |
| Duncan to Rio Rico (Arizona) | 785.06 mi (1,263.43 km) |
| Duncan to Ripon (California) | 1,310.28 mi (2,108.69 km) |
| Duncan to River Edge (New Jersey) | 1,372.42 mi (2,208.70 km) |
| Duncan to River Falls (Wisconsin) | 766.19 mi (1,233.06 km) |
| Duncan to River Forest (Illinois) | 746.62 mi (1,201.56 km) |
| Duncan to River Grove (Illinois) | 747.18 mi (1,202.46 km) |
