The most popular folk group of the 1960s, Peter, Paul and Mary in later decades have also proved themselves to be among the most durable music acts in history. Their longevity dwarfs that of the Weavers, while the fact that the trio continues to be associated with a major record label (Warner Bros.) after decades in the business sets them apart from rivals like the Kingston Trio and the Brothers Four. Then again, perhaps it isn't so surprising -- Peter, Paul and Mary's roots run deeper than almost any other folk act one might care to name, while their appeal crosses audience l...