There are
1,331 mi
from Port Arthur, TX to Gaithersburg, MD
That's the driving distance. It would take 1 day to go from Port Arthur, Texas to Gaithersburg, Maryland.
The flight distance (direct flight from Port Arthur, TX to Gaithersburg, MD) is 1,144.75 mi.
1,331 mi = 2,142.56 kms