Bill D - good for you, but didn't it have to be someone still gigging?
i guess that let's eubie out. pete seeger isn't singing in public much anymore - and he's a surefire draw, even singing with others, like the clearwater walkabout chorus. i was going to nominate jean ritchie - still singing to packed houses all over the world - and sounding great - she still has her high notes [nervous about them now and then] and her range has increased and her voice gets richer as she ages. she's 82 now [no tattling - she said so on stage recently] and another kind of longevity - oscar brand has had a weekly radio show on NPR for 50+ years - now that's longevity.