They sang the usual suspects - Bob Dylan, Pete Seeger, PP&M - but they sang some tunes that I hadn't really classified in the same genre as the folkies. For example, the Beatles showed up. More than once.
So what is folk music? Is it guitar-led acoustic instrumentation with a harmonized melody? Is it a song that everybody from a specific region knows well? Is it a song that is socially aware? A song that has been sung for generations?
I'm not sure anymore. I'm working on rewriting my definition. The fun thing is that this potential widening of folk music means we get to play some songs we might not have played before.
Case in point: