| Grass Valley to Olympia Heights (Florida) | 2,524.52 mi (4,062.82 km) |
| Grass Valley to Omaha (Nebraska) | 1,321.35 mi (2,126.51 km) |
| Grass Valley to On Top of the World Designated Place (Florida) | 2,304.13 mi (3,708.14 km) |
| Grass Valley to Onalaska (Wisconsin) | 1,567.33 mi (2,522.38 km) |
| Grass Valley to Oneida (New York) | 2,347.52 mi (3,777.96 km) |
| Grass Valley to Oneonta (New York) | 2,384.67 mi (3,837.75 km) |
| Grass Valley to Ontario (California) | 405.89 mi (653.22 km) |
| Grass Valley to Ontario (Oregon) | 392.83 mi (632.19 km) |
| Grass Valley to Opa-locka (Florida) | 2,522.54 mi (4,059.64 km) |
| Grass Valley to Opelika (Alabama) | 2,032.62 mi (3,271.19 km) |
| Grass Valley to Opelousas (Louisiana) | 1,739.59 mi (2,799.59 km) |
| Grass Valley to Orange (California) | 415.15 mi (668.13 km) |
| Grass Valley to Orange (Texas) | 1,665.26 mi (2,679.98 km) |
| Grass Valley to Orange City (Florida) | 2,362.91 mi (3,802.73 km) |
| Grass Valley to Orangeburg (South Carolina) | 2,252.01 mi (3,624.27 km) |
