| Boulder to Oak Harbor (Washington) | 1,030.11 mi (1,657.80 km) |
| Boulder to Oak Hills (Oregon) | 967.31 mi (1,556.74 km) |
| Boulder to Oak Lawn (Illinois) | 920.12 mi (1,480.80 km) |
| Boulder to Oak Park (California) | 845.66 mi (1,360.96 km) |
| Boulder to Oak Park (Illinois) | 918.60 mi (1,478.34 km) |
| Boulder to Oak Park (Michigan) | 1,155.54 mi (1,859.66 km) |
| Boulder to Oak Ridge (Florida) | 1,570.55 mi (2,527.55 km) |
| Boulder to Oak Ridge (New Jersey) | 1,608.29 mi (2,588.29 km) |
| Boulder to Oak Ridge (Tennessee) | 1,172.17 mi (1,886.43 km) |
| Boulder to Oakdale (California) | 851.90 mi (1,371.00 km) |
| Boulder to Oakdale (Minnesota) | 712.60 mi (1,146.82 km) |
| Boulder to Oakland (California) | 923.59 mi (1,486.38 km) |
| Boulder to Oakland (New Jersey) | 1,621.54 mi (2,609.61 km) |
| Boulder to Oakland Park (Florida) | 1,729.78 mi (2,783.81 km) |
| Boulder to Oakleaf Plantation (Florida) | 1,482.39 mi (2,385.68 km) |
