| Split to Olympia Heights (Florida) | 5,333.37 mi (8,583.24 km) |
| Split to Omaha (Nebraska) | 5,236.50 mi (8,427.33 km) |
| Split to On Top of the World Designated Place (Florida) | 5,264.01 mi (8,471.61 km) |
| Split to Onalaska (Wisconsin) | 4,933.78 mi (7,940.15 km) |
| Split to Oneida (New York) | 4,367.10 mi (7,028.17 km) |
| Split to Oneonta (New York) | 4,367.64 mi (7,029.04 km) |
| Split to Ontario (California) | 6,346.86 mi (10,214.28 km) |
| Split to Ontario (Oregon) | 5,741.89 mi (9,240.68 km) |
| Split to Opa-locka (Florida) | 5,321.35 mi (8,563.88 km) |
| Split to Opelika (Alabama) | 5,232.33 mi (8,420.63 km) |
| Split to Opelousas (Louisiana) | 5,617.39 mi (9,040.31 km) |
| Split to Orange (California) | 6,367.18 mi (10,246.98 km) |
| Split to Orange (Texas) | 5,706.69 mi (9,184.04 km) |
| Split to Orange City (Florida) | 5,227.32 mi (8,412.55 km) |
| Split to Orangeburg (South Carolina) | 4,999.74 mi (8,046.31 km) |
