There are
2,774 mi
from Gaithersburg, MD to Walnut Creek, CA
That's the driving distance. It would take 2 days to go from Gaithersburg, Maryland to Walnut Creek, California.
The flight distance (direct flight from Gaithersburg, MD to Walnut Creek, CA) is 2,401.57 mi.
2,774 mi = 4,464.49 kms