| Grayslake to Oswego (Illinois) | 48.00 mi (77.25 km) |
| Grayslake to Oswego (New York) | 588.32 mi (946.81 km) |
| Grayslake to Otsego (Minnesota) | 344.04 mi (553.68 km) |
| Grayslake to Ottawa (Illinois) | 79.34 mi (127.68 km) |
| Grayslake to Ottawa (Kansas) | 459.32 mi (739.20 km) |
| Grayslake to Ottumwa (Iowa) | 243.95 mi (392.60 km) |
| Grayslake to Overland (Missouri) | 280.02 mi (450.66 km) |
| Grayslake to Overland Park (Kansas) | 422.53 mi (680.00 km) |
| Grayslake to Overlea (Maryland) | 635.41 mi (1,022.59 km) |
| Grayslake to Oviedo (Florida) | 1,019.90 mi (1,641.37 km) |
| Grayslake to Owasso (Oklahoma) | 589.94 mi (949.42 km) |
| Grayslake to Owatonna (Minnesota) | 288.24 mi (463.88 km) |
| Grayslake to Owensboro (Kentucky) | 320.34 mi (515.53 km) |
| Grayslake to Owings Mills (Maryland) | 620.65 mi (998.85 km) |
| Grayslake to Owosso (Michigan) | 201.13 mi (323.68 km) |
