| Prospect Heights to Oakleaf Plantation (Florida) | 891.34 mi (1,434.47 km) |
| Prospect Heights to Oakley (California) | 1,796.54 mi (2,891.25 km) |
| Prospect Heights to Oakton (Virginia) | 600.31 mi (966.10 km) |
| Prospect Heights to Oakville (Missouri) | 282.32 mi (454.36 km) |
| Prospect Heights to Oatfield (Oregon) | 1,731.44 mi (2,786.48 km) |
| Prospect Heights to Ocala (Florida) | 949.54 mi (1,528.13 km) |
| Prospect Heights to Ocean Acres (New Jersey) | 729.98 mi (1,174.79 km) |
| Prospect Heights to Ocean City (New Jersey) | 724.23 mi (1,165.53 km) |
| Prospect Heights to Ocean Pines (Maryland) | 720.32 mi (1,159.24 km) |
| Prospect Heights to Ocean Pointe (Hawaii) | 4,241.17 mi (6,825.50 km) |
| Prospect Heights to Ocean Springs (Mississippi) | 809.50 mi (1,302.76 km) |
| Prospect Heights to Oceanside (California) | 1,709.68 mi (2,751.47 km) |
| Prospect Heights to Oceanside (New York) | 747.03 mi (1,202.23 km) |
| Prospect Heights to Ocoee (Florida) | 1,000.73 mi (1,610.52 km) |
| Prospect Heights to Oconomowoc (Wisconsin) | 74.62 mi (120.08 km) |
