| Healdsburg to Olympia Heights (Florida) | 2,615.10 mi (4,208.60 km) |
| Healdsburg to Omaha (Nebraska) | 1,426.24 mi (2,295.31 km) |
| Healdsburg to On Top of the World Designated Place (Florida) | 2,397.99 mi (3,859.20 km) |
| Healdsburg to Onalaska (Wisconsin) | 1,673.26 mi (2,692.85 km) |
| Healdsburg to Oneida (New York) | 2,453.44 mi (3,948.43 km) |
| Healdsburg to Oneonta (New York) | 2,490.54 mi (4,008.14 km) |
| Healdsburg to Ontario (California) | 431.06 mi (693.72 km) |
| Healdsburg to Ontario (Oregon) | 482.18 mi (775.99 km) |
| Healdsburg to Opa-locka (Florida) | 2,613.43 mi (4,205.90 km) |
| Healdsburg to Opelika (Alabama) | 2,129.65 mi (3,427.35 km) |
| Healdsburg to Opelousas (Louisiana) | 1,828.52 mi (2,942.72 km) |
| Healdsburg to Orange (California) | 435.60 mi (701.03 km) |
| Healdsburg to Orange (Texas) | 1,751.69 mi (2,819.07 km) |
| Healdsburg to Orange City (Florida) | 2,457.15 mi (3,954.40 km) |
| Healdsburg to Orangeburg (South Carolina) | 2,351.87 mi (3,784.97 km) |
