Historical clue formulations

• Airport near Olympia, informally — 2023-02-08
• Washington hub that's a portmanteau of two cities — 2022-11-05
• Northwest airport, familiarly — 2021-04-06
• Airport named for two Washington cities — 2019-10-13
• Delta Air Lines hub — 2019-06-16
• Alaska Airlines hub — 2019-03-17
• Washington air hub — 2018-12-30
• Pacific Northwest hub, informally — 2018-10-04
• Evergreen State airport — 2017-03-05
• Alaska Airlines hub — 2016-04-16
• Northwest airport named for two cities — 2015-12-13
• Washington State airport — 2008-08-03
• Washington State airport — 1997-07-22
• The Mariners' airport — 1996-09-29