There are
2,606 mi
from Rosemead, CA to Gaithersburg, MD
That's the driving distance. It would take 1 day 22 hours to go from Rosemead, California to Gaithersburg, Maryland.
The flight distance (direct flight from Rosemead, CA to Gaithersburg, MD) is 2,274.22 mi.
2,606 mi = 4,194.12 kms