Well, I automatically think Irish music (especially in the coal mining areas, but all over PA, really), Philly Folk Festival, the Polish-American String Band, Slav tamburitzans, the Scots Irish along the Susquehanna & the canal builders who have left a lot of musicians in their wake, the German folk music of the Central Market & Lancaster that has always drawn folkies to it, even if just as a place of residence, Philly soul, jazz, doo wop, right on down today's neo-soul, a ton of labor music, all that church camp music from the summer church camps up in the Appalachian mountains, SUsquehanna Folk Music Society, Philly Folk Song Society, bars like Warmdaddys...

I certainly think folk music when I think of Philly & it's environs!