| Halstead to Olympia Heights (Florida) | 4,463.87 mi (7,183.91 km) |
| Halstead to Omaha (Nebraska) | 4,302.46 mi (6,924.14 km) |
| Halstead to On Top of the World Designated Place (Florida) | 4,373.55 mi (7,038.56 km) |
| Halstead to Onalaska (Wisconsin) | 3,999.78 mi (6,437.03 km) |
| Halstead to Oneida (New York) | 3,446.30 mi (5,546.29 km) |
| Halstead to Oneonta (New York) | 3,449.46 mi (5,551.38 km) |
| Halstead to Ontario (California) | 5,425.24 mi (8,731.08 km) |
| Halstead to Ontario (Oregon) | 4,837.52 mi (7,785.24 km) |
| Halstead to Opa-locka (Florida) | 4,451.40 mi (7,163.83 km) |
| Halstead to Opelika (Alabama) | 4,321.74 mi (6,955.17 km) |
| Halstead to Opelousas (Louisiana) | 4,697.85 mi (7,560.47 km) |
| Halstead to Orange (California) | 5,445.63 mi (8,763.89 km) |
| Halstead to Orange (Texas) | 4,784.90 mi (7,700.55 km) |
| Halstead to Orange City (Florida) | 4,340.81 mi (6,985.86 km) |
| Halstead to Orangeburg (South Carolina) | 4,097.73 mi (6,594.66 km) |
