Stands more limited in size extend up the valleys and foothills of the southern Blue Mountain region, and small groups or individuals are scattered sparsely through the northern Blue Mountains. It is found near Mount Ashland in southwestern Oregon, the only native stand documented west of the Cascade Range in Oregon. It grows in scattered locations west of the Cascades in northern California and extends south to Trinity County. Western juniper is present in extensive stands from the Oregon border south through the Pit River Valley in northeastern California and continues intermittently as sparse stands in a narrow corridor along eastern California south to disjunct stands in the San Bernardino Mountains. The eastern limits of this species are in San Bernardino County, California, and Owyhee County, Idaho.
Western Juniper occurs primarily on dry mountain slopes or plateaus, usually on rocky soils.
Silvics of North America, U.S. Forest Service . Climate-Vegetation Atlas, U.S. Geological Survey . CalFlora Database . Flora of North America . Gymnosperm Database .