Historical clue formulations

• First in a field — 2018-04-19
• First of a kind — 2014-05-04
• Daniel Boone, notably — 2013-04-22
• Innovator — 2012-01-19
• Davy Crockett, e.g. — 2011-12-20
• NASA program that explored the outer planets — 2008-11-18
• Avant-gardist — 1998-06-27
• Show the way — 1995-10-15
• Avant-gardist — 1994-06-27