| Grantsville to Olympia Heights (Florida) | 2,107.41 mi (3,391.54 km) |
| Grantsville to Omaha (Nebraska) | 857.16 mi (1,379.47 km) |
| Grantsville to On Top of the World Designated Place (Florida) | 1,874.92 mi (3,017.39 km) |
| Grantsville to Onalaska (Wisconsin) | 1,107.79 mi (1,782.82 km) |
| Grantsville to Oneida (New York) | 1,887.28 mi (3,037.29 km) |
| Grantsville to Oneonta (New York) | 1,923.38 mi (3,095.38 km) |
| Grantsville to Ontario (California) | 534.37 mi (859.99 km) |
| Grantsville to Ontario (Oregon) | 329.08 mi (529.60 km) |
| Grantsville to Opa-locka (Florida) | 2,104.23 mi (3,386.42 km) |
| Grantsville to Opelika (Alabama) | 1,592.08 mi (2,562.21 km) |
| Grantsville to Opelousas (Louisiana) | 1,336.63 mi (2,151.10 km) |
| Grantsville to Orange (California) | 554.65 mi (892.63 km) |
| Grantsville to Orange (Texas) | 1,275.32 mi (2,052.43 km) |
| Grantsville to Orange City (Florida) | 1,931.91 mi (3,109.11 km) |
| Grantsville to Orangeburg (South Carolina) | 1,800.36 mi (2,897.41 km) |
