There are
2,804 mi
from Gaithersburg, MD to Pacifica, CA
That's the driving distance. It would take 2 days 1 hour to go from Gaithersburg, Maryland to Pacifica, California.
The flight distance (direct flight from Gaithersburg, MD to Pacifica, CA) is 2,429.43 mi.
2,804 mi = 4,512.22 kms