| Lake Monticello to Olympia Heights (Florida) | 850.88 mi (1,369.36 km) |
| Lake Monticello to Omaha (Nebraska) | 969.60 mi (1,560.43 km) |
| Lake Monticello to On Top of the World Designated Place (Florida) | 650.14 mi (1,046.31 km) |
| Lake Monticello to Onalaska (Wisconsin) | 787.46 mi (1,267.30 km) |
| Lake Monticello to Oneida (New York) | 382.75 mi (615.98 km) |
| Lake Monticello to Oneonta (New York) | 357.42 mi (575.22 km) |
| Lake Monticello to Ontario (California) | 2,196.10 mi (3,534.29 km) |
| Lake Monticello to Ontario (Oregon) | 2,040.16 mi (3,283.33 km) |
| Lake Monticello to Opa-locka (Florida) | 838.17 mi (1,348.91 km) |
| Lake Monticello to Opelika (Alabama) | 538.23 mi (866.19 km) |
| Lake Monticello to Opelousas (Louisiana) | 935.62 mi (1,505.74 km) |
| Lake Monticello to Orange (California) | 2,213.02 mi (3,561.52 km) |
| Lake Monticello to Orange (Texas) | 1,032.90 mi (1,662.29 km) |
| Lake Monticello to Orange City (Florida) | 643.79 mi (1,036.08 km) |
| Lake Monticello to Orangeburg (South Carolina) | 337.42 mi (543.03 km) |
