There are
1,330 mi
from Garland, TX to Gaithersburg, MD
That's the driving distance. It would take 23 hours 55 mins to go from Garland, Texas to Gaithersburg, Maryland.
The flight distance (direct flight from Garland, TX to Gaithersburg, MD) is 1,165.36 mi.
1,330 mi = 1.61 kms