There are
2,589 mi
from Gaithersburg, MD to Pomona, CA
That's the driving distance. It would take 1 day 22 hours to go from Gaithersburg, Maryland to Pomona, California.
The flight distance (direct flight from Gaithersburg, MD to Pomona, CA) is 2,257.69 mi.
2,589 mi = 4,166.95 kms