There are
2,616 mi
from Gaithersburg, MD to Downey, CA
That's the driving distance. It would take 1 day 22 hours to go from Gaithersburg, Maryland to Downey, California.
The flight distance (direct flight from Gaithersburg, MD to Downey, CA) is 2,280.92 mi.
2,616 mi = 4,210.26 kms