It's an interesting question. Have you read Gregg Smith's Beer in America: The Early Years? There might be something in there. You could also try to contact Yuengling to see if they have any archives you could go through. You could also local newspaper archives for references to Yuengling as well -- they are the primary employer of that area, so they clearly have a significant cultural impact.
The AHA might have some data regarding the growth of homebrew clubs & stores in PA. Then you could possibly contact some members of those clubs -- particularly the older clubs -- for interviews regarding the growth and spread of homebrewing.
Two Kids Brewery
Primary: Empty :(
Seconary: Don't use one, generally
Kegged: Pumpkin Saison, Amber Ale
Planned: Scottish Strong Ale
"For a quart of ale is a dish for a king." - Shakespeare