| Canals to Olympia Heights (Florida) | 4,599.99 mi (7,402.97 km) |
| Canals to Omaha (Nebraska) | 4,764.75 mi (7,668.13 km) |
| Canals to On Top of the World Designated Place (Florida) | 4,572.38 mi (7,358.54 km) |
| Canals to Onalaska (Wisconsin) | 4,459.53 mi (7,176.91 km) |
| Canals to Oneida (New York) | 3,789.79 mi (6,099.08 km) |
| Canals to Oneonta (New York) | 3,779.03 mi (6,081.76 km) |
| Canals to Ontario (California) | 5,983.76 mi (9,629.93 km) |
| Canals to Ontario (Oregon) | 5,467.74 mi (8,799.47 km) |
| Canals to Opa-locka (Florida) | 4,588.95 mi (7,385.20 km) |
| Canals to Opelika (Alabama) | 4,594.65 mi (7,394.37 km) |
| Canals to Opelousas (Louisiana) | 5,004.39 mi (8,053.78 km) |
| Canals to Orange (California) | 6,004.05 mi (9,662.58 km) |
| Canals to Orange (Texas) | 5,101.93 mi (8,210.76 km) |
| Canals to Orange City (Florida) | 4,527.95 mi (7,287.03 km) |
| Canals to Orangeburg (South Carolina) | 4,341.96 mi (6,987.71 km) |
