The shortest driving distance is 787 miles.
794 miles
It is 797.46 miles according to MapQuest.
It is 633.1 miles according to MapQuest.
It really does depend what part of the state you travel too. I am going to use Montgomery (the state captial of Alabama) and Austin (the state capital of Texas). Following the I-10 going West, you can reach Austin in 12 hours and 56 minutes (which is a distance of 794 miles).
670 miles
106 miles
93 miles
51 miles
168 miles
Austin to Dallas, 195 miles Austin to Pittsburgh, 1417 miles Austin to Philadelphia, 1682 miles
55 miles
Montgomery Alabama is about 20 miles wide and about as long.