| National City to Oakley (California) | 450.01 mi (724.21 km) |
| National City to Oakton (Virginia) | 2,253.58 mi (3,626.79 km) |
| National City to Oakville (Missouri) | 1,551.23 mi (2,496.46 km) |
| National City to Oatfield (Oregon) | 928.22 mi (1,493.82 km) |
| National City to Ocala (Florida) | 2,076.08 mi (3,341.13 km) |
| National City to Ocean Acres (New Jersey) | 2,413.20 mi (3,883.67 km) |
| National City to Ocean City (New Jersey) | 2,397.37 mi (3,858.20 km) |
| National City to Ocean Pines (Maryland) | 2,371.18 mi (3,816.04 km) |
| National City to Ocean Pointe (Hawaii) | 2,621.16 mi (4,218.34 km) |
| National City to Ocean Springs (Mississippi) | 1,669.61 mi (2,686.98 km) |
| National City to Oceanside (California) | 40.52 mi (65.21 km) |
| National City to Oceanside (New York) | 2,445.48 mi (3,935.62 km) |
| National City to Ocoee (Florida) | 2,123.48 mi (3,417.42 km) |
| National City to Oconomowoc (Wisconsin) | 1,707.21 mi (2,747.49 km) |
| National City to Odenton (Maryland) | 2,285.89 mi (3,678.78 km) |
