Historical clue formulations

• Innermost — 2021-04-21
• Division of baseball's N.L. or A.L. — 2017-08-08
• Key — 2017-07-22
• With 68-Across, the circled part of this crossword — 2017-04-27
• Key — 2010-05-07
• Dominant — 2007-04-05
• Prime — 2006-06-18
• Not extreme — 2005-08-14
• Like some air-conditioning — 2005-03-29
• Key — 2003-09-18
• N.F.C. or A.F.C. division — 2002-05-28
• Main — 1996-01-29
• Indispensable — 1994-09-16
• Old telephone exchange — 1994-09-08