| Thornton to Olympia Heights (Florida) | 4,342.10 mi (6,987.94 km) |
| Thornton to Omaha (Nebraska) | 4,147.48 mi (6,674.72 km) |
| Thornton to On Top of the World Designated Place (Florida) | 4,244.41 mi (6,830.72 km) |
| Thornton to Onalaska (Wisconsin) | 3,845.59 mi (6,188.87 km) |
| Thornton to Oneida (New York) | 3,304.55 mi (5,318.16 km) |
| Thornton to Oneonta (New York) | 3,309.20 mi (5,325.64 km) |
| Thornton to Ontario (California) | 5,263.30 mi (8,470.47 km) |
| Thornton to Ontario (Oregon) | 4,673.60 mi (7,521.43 km) |
| Thornton to Opa-locka (Florida) | 4,329.50 mi (6,967.65 km) |
| Thornton to Opelika (Alabama) | 4,184.31 mi (6,734.00 km) |
| Thornton to Opelousas (Louisiana) | 4,555.71 mi (7,331.71 km) |
| Thornton to Orange (California) | 5,283.68 mi (8,503.26 km) |
| Thornton to Orange (Texas) | 4,641.47 mi (7,469.72 km) |
| Thornton to Orange City (Florida) | 4,213.21 mi (6,780.50 km) |
| Thornton to Orangeburg (South Carolina) | 3,964.36 mi (6,380.01 km) |
