This "Wildest Trail in Pennsylvania" runs for 319 miles (513 km) right across the state. It leads through the Appalachians and across Allegheny Plateau.
Official site of Mid State Trail, with the most current and complete information about - what they claim - "Pennsylvania's longest and wildest footpath"
Another description of the trail.
Introduction to the MST
Short intro and a map. Elsewhere on this website you will find some trip reports as well.
Advice / journalist impression.
And an article by the Sierra Club of Pennsylvania.
On this page you will find some pages regarding the MST, and some other trails as well.
Some opinions of different people.
Some pictures of the trail and some opinions.
Mix of opinion and trip report.