| Boulder to Ridgeland (Mississippi) | 990.17 mi (1,593.53 km) |
| Boulder to Ridgewood (New Jersey) | 1,628.62 mi (2,621.01 km) |
| Boulder to Rifle (Colorado) | 138.02 mi (222.12 km) |
| Boulder to Rincon (Georgia) | 1,436.63 mi (2,312.04 km) |
| Boulder to Ringwood (New Jersey) | 1,619.08 mi (2,605.65 km) |
| Boulder to Río Grande (Puerto Rico) | 2,774.97 mi (4,465.89 km) |
| Boulder to Rio Grande City (Texas) | 1,012.61 mi (1,629.64 km) |
| Boulder to Rio Linda (California) | 868.61 mi (1,397.89 km) |
| Boulder to Rio Rancho (New Mexico) | 336.73 mi (541.92 km) |
| Boulder to Rio Rico (Arizona) | 670.96 mi (1,079.81 km) |
| Boulder to Ripon (California) | 867.23 mi (1,395.68 km) |
| Boulder to River Edge (New Jersey) | 1,632.98 mi (2,628.02 km) |
| Boulder to River Falls (Wisconsin) | 724.27 mi (1,165.60 km) |
| Boulder to River Forest (Illinois) | 917.11 mi (1,475.94 km) |
| Boulder to River Grove (Illinois) | 916.24 mi (1,474.54 km) |
