Historical clue formulations

• Is behind — 2022-06-23
• Hiking paths — 2022-01-31
• "Happy ___!" — 2021-08-14
• Backpackers' routes — 2016-12-20
• Lags — 2016-12-11
• Straggles — 2016-12-04
• Ski runs, e.g. — 2008-10-05
• Ranger's knowledge — 2002-02-16
• Is behind — 2001-01-21
• Park features — 1999-01-25
• Is behind — 1997-02-15
• "Happy _____" — 1995-05-20