There are
2,761 mi
from Gaithersburg, MD to Vallejo, CA
That's the driving distance. It would take 2 days to go from Gaithersburg, Maryland to Vallejo, California.
The flight distance (direct flight from Gaithersburg, MD to Vallejo, CA) is 2,407.79 mi.
2,761 mi = 4,443.61 kms