Therefore , the Piedmont Mountains in the Southeast occur less frequently ( in a larger area ) and are more prominent .
Almost ninety percent of the Piedmont lies south below the Mason -- Dixon Line before permeating into the New England region .
The Piedmont Mountains in the Southeast occur less frequently ( in a larger area ) and are more prominent .
Almost ninety percent of the Piedmont lies south below the Mason -- Dixon Line before permeating into the New England region .