| Rockville to Oakleaf Plantation (Florida) | 670.64 mi (1,079.30 km) |
| Rockville to Oakley (California) | 2,383.87 mi (3,836.46 km) |
| Rockville to Oakton (Virginia) | 15.58 mi (25.07 km) |
| Rockville to Oakville (Missouri) | 709.95 mi (1,142.56 km) |
| Rockville to Oatfield (Oregon) | 2,332.80 mi (3,754.28 km) |
| Rockville to Ocala (Florida) | 741.31 mi (1,193.02 km) |
| Rockville to Ocean Acres (New Jersey) | 160.07 mi (257.61 km) |
| Rockville to Ocean City (New Jersey) | 137.35 mi (221.04 km) |
| Rockville to Ocean Pines (Maryland) | 118.42 mi (190.58 km) |
| Rockville to Ocean Pointe (Hawaii) | 4,828.78 mi (7,771.17 km) |
| Rockville to Ocean Springs (Mississippi) | 890.38 mi (1,432.92 km) |
| Rockville to Oceanside (California) | 2,257.64 mi (3,633.32 km) |
| Rockville to Oceanside (New York) | 215.13 mi (346.22 km) |
| Rockville to Ocoee (Florida) | 767.73 mi (1,235.54 km) |
| Rockville to Oconomowoc (Wisconsin) | 651.70 mi (1,048.80 km) |
