| Boulder to Ukiah (California) | 956.54 mi (1,539.40 km) |
| Boulder to Union (Missouri) | 770.12 mi (1,239.39 km) |
| Boulder to Union City (California) | 916.54 mi (1,475.03 km) |
| Boulder to Union City (Georgia) | 1,224.12 mi (1,970.03 km) |
| Boulder to Union City (New Jersey) | 1,634.91 mi (2,631.13 km) |
| Boulder to Union City (Tennessee) | 912.55 mi (1,468.61 km) |
| Boulder to Union Hill-Novelty Hill (Washington) | 985.92 mi (1,586.68 km) |
| Boulder to Union Park (Florida) | 1,575.55 mi (2,535.61 km) |
| Boulder to Uniondale (New York) | 1,658.07 mi (2,668.41 km) |
| Boulder to Universal City (Texas) | 823.27 mi (1,324.92 km) |
| Boulder to University (Florida) | 1,538.19 mi (2,475.48 km) |
| Boulder to University City (Missouri) | 801.81 mi (1,290.40 km) |
| Boulder to University Heights (Ohio) | 1,241.49 mi (1,997.98 km) |
| Boulder to University of California-Santa Barbara (California) | 890.62 mi (1,433.32 km) |
| Boulder to University Park (Texas) | 682.55 mi (1,098.46 km) |
