I would say roughly about 4 to 5 days driveing time.
A long time
If you are asking about the Cornwall in England, then you can't drive from there to Los Angeles, because of the ocean.
few days
50 hours
One side of North America to the other is about 73 hours.
about 45 mins
37 hours
About 8 hours of driving time.
About 37 1/2 hours.
walk..
5 hours and 52 minutes.
44 hours