How do the Appalachian mountains act as a barrier to colonization?

Question

How do the Appalachian mountains act as a barrier to colonization?

Answer 1

They were huge mountains and they had to get past them

Answer 2

Trish is correct.  Daniel Boone got through with his "wilderness road."  Atlanta, Ga., at the southern end of the mountain chain, became a major railroad center because it was easier to build railroads around the southern end of the chain than to go straight west, through the mountains.

Answer 3

They were a physical barrier; if you're going to colonize west of the mountains, you have to be able to GET there, and that was a problem.