| Quarteira to Olympia Heights (Florida) | 4,232.17 mi (6,811.02 km) |
| Quarteira to Omaha (Nebraska) | 4,506.88 mi (7,253.12 km) |
| Quarteira to On Top of the World Designated Place (Florida) | 4,221.89 mi (6,794.48 km) |
| Quarteira to Onalaska (Wisconsin) | 4,205.15 mi (6,767.53 km) |
| Quarteira to Oneida (New York) | 3,499.02 mi (5,631.13 km) |
| Quarteira to Oneonta (New York) | 3,483.19 mi (5,605.66 km) |
| Quarteira to Ontario (California) | 5,755.50 mi (9,262.58 km) |
| Quarteira to Ontario (Oregon) | 5,286.07 mi (8,507.11 km) |
| Quarteira to Opa-locka (Florida) | 4,221.61 mi (6,794.02 km) |
| Quarteira to Opelika (Alabama) | 4,266.69 mi (6,866.58 km) |
| Quarteira to Opelousas (Louisiana) | 4,682.73 mi (7,536.13 km) |
| Quarteira to Orange (California) | 5,775.48 mi (9,294.74 km) |
| Quarteira to Orange (Texas) | 4,782.73 mi (7,697.06 km) |
| Quarteira to Orange City (Florida) | 4,174.62 mi (6,718.40 km) |
| Quarteira to Orangeburg (South Carolina) | 4,007.97 mi (6,450.20 km) |
