Historical clue formulations

• Part of Canada above Alta. and Sask. — 2020-08-09
• It's above Alta. and Sask. — 2013-03-19
• Its capital is Yellowknife: Abbr. — 2013-01-06
• Yellowknife is its cap. — 2009-06-21
• Yukon neighbor: Abbr. — 2008-02-21