Historical clue formulations

• Winter hrs. in Salt Lake City — 2025-10-07
• Denver setting: Abbr. — 2025-07-16
• Rockies setting: Abbr. — 2024-07-27
• Denver winter hrs. — 2023-02-01
• Winter hrs. in Denver — 2022-07-26
• Year-round Phoenix hrs. — 2021-03-14
• Winter hrs. in Yellowstone — 2020-10-16
• Winter Wyoming hrs. — 2019-08-01
• Tucson hrs. — 2017-07-28
• Winter hrs. in Vail — 2017-03-12
• Colorado winter hrs. — 2017-01-30
• Boulder setting: Abbr. — 2016-12-23
• El Paso setting: Abbr. — 2015-12-20
• Winter hrs. in Calgary — 2015-05-12
• Tucson hrs. — 2015-04-02
• Yellowstone setting: Abbr. — 2013-08-30
• Phoenix setting: Abbr. — 2013-05-10
• N.M. setting — 2013-04-07
• ID tag? — 2013-02-01
• Winter Denver hrs. — 2013-01-22
• Ft. Collins setting — 2011-02-27
• Phoenix hrs. — 2011-02-06
• Winter hours in Colo. — 2010-04-29
• Boulder hrs. — 2007-08-16
• Abbr. on Rockies skeds — 2007-08-12
• Colorado hrs. — 2006-08-23
• Two hrs. earlier than N.Y. — 2004-11-26
• Denver clock setting: Abbr. — 2003-08-19
• Colo. is on it — 2002-12-26
• Salt Lake City zone: Abbr. — 2002-11-18
• Colo. is on it — 2001-12-14
• Colo. clock setting — 2000-10-07
• Denver clock setting: Abbr. — 2000-04-27
• It's observed in Jan. in the Rockies — 1999-07-06
• Colo. clock setting — 1999-05-25
• Colo. hours — 1998-09-18
• Rockies zone: Abbr. — 1996-10-12
• Denver zone: Abbr. — 1995-02-04
• Denver zone: Abbr. — 1995-01-21