There are
2,788 mi
from Gaithersburg, MD to San Anselmo, CA
That's the driving distance. It would take 2 days to go from Gaithersburg, Maryland to San Anselmo, California.
The flight distance (direct flight from Gaithersburg, MD to San Anselmo, CA) is 2,426.23 mi.
2,788 mi = 4,487.60 kms