Historical clue formulations

• Country club? — 2026-09-18
• Organization honored on October 24 ... and the theme of this puzzle — 2018-12-05
• Organization founded in 1945 ... or a literal description of 20-, 24- and 44-Across? — 2017-04-11
• Annual October 24 honoree — 2005-05-05
• Organization founded in 1945 — 1995-07-23