Historical clue formulations

• 1971 hit with the lyric "He danced for those at minstrel shows" — 2007-06-08
• Famous tap-dancer — 2002-05-27
• Nitty Gritty Dirt Band hit, 1971 — 2000-02-17
• 1971 Nitty Gritty Dirt Band song — 1995-05-09