Historical clue formulations

• Workers' rights grp. — 2025-04-16
• U.S.'s largest alliance of trade unions — 2021-08-31
• Big workers' group — 2019-03-04
• Big workers' grp. since 1955 — 2018-07-24
• Big workers' grp. — 2017-09-27
• Grp. formed in a 1955 merger — 2015-12-09
• Union union — 2015-04-05
• Result of a '55 union merger — 2011-08-24
• Org. with a handshake in its logo — 2010-04-23
• George Meany's org. — 2005-04-26
• 1955 merger — 1998-06-30