The high elevation subalpine and montane forests of the Rocky Mountains often have Engelmann spruce as a major tree species in their composition. A distribution map illustrating the broad western North American distribution can be viewed via the USDA Forest Service’s Silvics of North America entry on Picea engelmannii. Note that Engelmann spruce can also be found within the Coast-Cascade Mountains and some of the high-elevation areas between the two mountainous belts.
A second subspecies of Picea engelmannii is recognized, subspecies mexicana. It is known from populations in Mexico and (some say) the Chiricahua Mountains. The Gymnosperm Database’s entry on Picea engelmannii suggests that subspecies mexicana is found in the USA, while the Flora of North America concludes otherwise.