Historical clue formulations

• State capital in the Treasure Valley — 2026-06-28
• State capital in the so-called "Treasure Valley" — 2022-04-06
• Capital near the old Oregon Trail — 2021-10-29
• U.S. city that's home to the largest Basque population outside Spain — 2021-05-14
• Capital known as the City of Trees — 2019-03-30
• City on the Oregon Trail — 2017-10-06
• Western capital — 2017-03-19
• Place where you need an ID to get mail? — 2016-03-09
• ___ State (Mountain West Conference team) — 2014-03-30
• Idaho's capital — 2012-12-17
• Idaho's capital — 2012-12-04
• Capital of Idaho — 2012-04-09
• State capital whose name comes from the French for "wooded area" — 2011-08-28
• Snake feeder — 2009-08-15
• Capital nicknamed "City of Trees" — 2007-04-15
• Oregon Trail city — 2001-07-01
• City of Trees — 2001-03-25
• Gem State capital — 1999-08-31
• Capital NW of Twin Falls — 1998-06-16
• Oregon Trail fort — 1998-04-03
• City on the Oregon Trail — 1997-07-20
• State capital or its river — 1997-04-09
• Arrowrock Dam's river — 1996-09-07
• Idaho river — 1996-05-25
• Idaho city — 1994-05-10
• Fort on the Oregon Trail — 1993-12-31