Many veteran bands trade on nostalgia, on replication of past glories, and on recycled emo-tions from younger, more carefree days. The Nitty Gritty Dirt Band trades on a mix of reimagined classics and compelling newer works. The group formed in 1966 as a Long Beach, California jug band, scored its first charting single in 1967, and embarked on a self-propelled ride through folk, country, rock ‘n’ roll, pop, blue-grass, and the amalgam now known as “Americana.” The first major hit came in 1971 with the epic “Mr. Bojangles,” which, along with insistent support from banjo master Earl Scruggs, opened doors in Nashville. Behind those doors were Earl Scruggs, Roy Acuff, Doc Watson, Mother Maybelle Carter, Jimmy Martin, and others who would collaborate on a multi-artist, multi-generational, three-disc 1972 masterpiece: Will the Circle Be Unbroken went triple Platinum, spawned two later volumes, and wound up in the Grammy Hall of Fame.