Aspen is the most widely distributed tree species in North America, ranging from Alaska to Newfoundland and down the Rocky Mountains to Mexico. Interestingly, Utah and Colorado is home to the largest portion of the natural acreage of aspen in the World.
Here is the
aspen range in North America.
Aspen stars in the greatest fall color show going west of the Mississippi River. As an aspen leaf's chlorophyll fades, a group of colored pigments called carotenoids show. Like chlorophyll, carotenoids are contained in the plastids, tiny structures in leaf cells. Carotenoids are the yellow we see each fall in aspens.