The
Blue Mountains are a mountain range in the western
United States, located largely in northeastern
Oregon and stretching into southeastern
Washington. The range has an area of , stretching east and southeast of
Pendleton, Oregon, to the
Snake River along the Oregon-
Idaho border. The Blue Mountains cover seven counties in Oregon and Washington; they are
Union,
Umatilla,
Grant,
Baker, and
Wallowa counties in Oregon, and
Walla Walla,
Columbia and
Garfield counties in Washington. They are home to the world's largest organism and fungal mycelial mat, the
Armillaria solidipes.