The Sublett Range is a mountain range in Idaho (~94%) and Utah (~6%) in the United States, spanning Cassia, Oneida, and Power counties, Idaho and reaching into Box Elder County, Utah.[1][2] The Phosphoria Formation reaches its greatest thickness beneath the mountains.[5] The range was named after the trapper William Sublette, who lived in the area in the 1830s.Most of the mountains are covered in sagebrush steppe and meadows, but there can be pockets of Douglas fir on northern slopes.This Cassia County, Idaho state location article is a stub.