| Napa to Olympia Heights (Florida) | 2,582.06 mi (4,155.42 km) |
| Napa to Omaha (Nebraska) | 1,403.25 mi (2,258.31 km) |
| Napa to On Top of the World Designated Place (Florida) | 2,366.20 mi (3,808.03 km) |
| Napa to Onalaska (Wisconsin) | 1,654.00 mi (2,661.85 km) |
| Napa to Oneida (New York) | 2,434.02 mi (3,917.17 km) |
| Napa to Oneonta (New York) | 2,470.59 mi (3,976.03 km) |
| Napa to Ontario (California) | 393.74 mi (633.67 km) |
| Napa to Ontario (Oregon) | 482.85 mi (777.07 km) |
| Napa to Opa-locka (Florida) | 2,580.48 mi (4,152.88 km) |
| Napa to Opelika (Alabama) | 2,099.38 mi (3,378.63 km) |
| Napa to Opelousas (Louisiana) | 1,795.08 mi (2,888.90 km) |
| Napa to Orange (California) | 398.64 mi (641.55 km) |
| Napa to Orange (Texas) | 1,717.55 mi (2,764.13 km) |
| Napa to Orange City (Florida) | 2,425.50 mi (3,903.47 km) |
| Napa to Orangeburg (South Carolina) | 2,323.26 mi (3,738.93 km) |
