There are
1,515 mi
from Great Falls, MT to Watauga, TX
That's the driving distance. It would take 1 day 2 hours to go from Great Falls, Montana to Watauga, Texas.
The flight distance (direct flight from Great Falls, MT to Watauga, TX) is 1,250.10 mi.
1,515 mi = 2,438.63 kms