Historical clue formulations

• Arizona county or Indigenous people — 2025-09-28
• County that's split in two by the Grand Canyon — 2021-09-25
• People indigenous to the Colorado River — 2018-06-02
• Native Arizonan — 2014-11-13
• Southwest desert that includes Death Valley — 2012-05-21
• American desert — 2006-04-05
• Much of San Bernardino County — 2003-06-05
• Native Arizonan — 2001-11-07