| Giffnock to Olympia Heights (Florida) | 4,231.40 mi (6,809.78 km) |
| Giffnock to Omaha (Nebraska) | 3,995.16 mi (6,429.59 km) |
| Giffnock to On Top of the World Designated Place (Florida) | 4,125.01 mi (6,638.57 km) |
| Giffnock to Onalaska (Wisconsin) | 3,694.51 mi (5,945.74 km) |
| Giffnock to Oneida (New York) | 3,170.52 mi (5,102.45 km) |
| Giffnock to Oneonta (New York) | 3,177.07 mi (5,113.00 km) |
| Giffnock to Ontario (California) | 5,100.30 mi (8,208.13 km) |
| Giffnock to Ontario (Oregon) | 4,506.77 mi (7,252.95 km) |
| Giffnock to Opa-locka (Florida) | 4,218.66 mi (6,789.28 km) |
| Giffnock to Opelika (Alabama) | 4,054.84 mi (6,525.63 km) |
| Giffnock to Opelousas (Louisiana) | 4,420.05 mi (7,113.38 km) |
| Giffnock to Orange (California) | 5,120.65 mi (8,240.89 km) |
| Giffnock to Orange (Texas) | 4,504.12 mi (7,248.68 km) |
| Giffnock to Orange City (Florida) | 4,095.70 mi (6,591.40 km) |
| Giffnock to Orangeburg (South Carolina) | 3,840.11 mi (6,180.07 km) |
