It is found in the Rocky Mountains in Colorado and northern New Mexico, with an isolated population in the San Francisco Peaks of Arizona.

It is found at very high altitudes, from 2,100 to 4,000 meters (6,900 to 13,100 ft) in cold, dry subalpine climate conditions, often at the tree line, although it also forms extensive closed-canopy stands at somewhat lower elevations.

In favorable conditions they are straight and upright trees, but they become increasingly stunted, short, and twisted the closer they grow to timberline.

[5] Twigs and very young branches are covered in needles that last for 10 to 17 years, giving them a shaggy bottle brush appearance.

Based on size and appearance scientists estimate there are 30 more trees in the same general area older than 1600 years that have not yet had core samples taken.

[6] At lower elevations in montane habitats where they grow with grasses, ages generally do not exceed 300 years.

[3] This reassessment was initially accepted by botanists such as Charles Sprague Sargent,[16] but was rejected by others such as Edward James Ravenscroft.

[19] Prior to work by Dana K. Bailey published in 1971, Pinus longaeva trees growing in California, Nevada, and Utah were not identified as a separate species or subspecies.

[22] The species name aristata means "bristle" in botanical Latin, a reference to the long points on the ends of the scales of its cones.

[28] The Rocky Mountain bristle cone reaches its northern limit at approximately 40 degrees north latitude.

[30] Rocky Mountain bristlecone will grow in krummholz habitat at the edge of the arctic tundra, where it has the typical dwarfed and gnarled growth of these "crooked woods".

[31] Its habitat extends downward into the subalpine forests and even lower in the driest parts of the middle elevations.

[32] The bristlecones and limber pines (Pinus flexilis) will grow into full trees at elevations where silver spruces (Picea engelmannii) and subalpine firs (Abies lasiocarpa) are reduced to stunted, ground hugging shrubs.

Their greater tolerance of dry conditions is what enables them to grow more successfully in challenging mountain habitats.

[32] In the Southern Rocky Mountains they, like the limber pine, may grow in extensive stands on some sites without other species of tree or may be found intermixed with them.

In the southerly parts of the Sangre de Cristo Range they replace the limber pines at higher elevations on very dry sites.

[22] A very large bristlecone pine wood of 120 hectares (300 acres) grows in the Valle Vidal within the Carson National Forest.

[35] In Colorado there are more than 50 areas with notable populations of bristlecone pine found in the southern and central mountain ranges of the state.

[35] The International Union for Conservation of Nature last evaluated Pinus aristata in 2012 and listed it as one of their species of "least concern".

The evaluation found its population was stable without a continuing decline of mature individuals, but with a naturally very fragmented habitat.

[2] In Arizona the state lists it as a salvage resiricted native plant, one that requires a permit for removal including on private land.

[40] The oldest tree in Colorado is a Rocky Mountain bristlecone that was dated by F. Craig Brunstein and David Yamaguchi to 442 BCE.

At the time core samples were taken by researchers the trees showed many signs of old age including dead wood that had been sculpted by wind erosion, crowns that had died back, only strips of living bark, and a radius greater than 40 centimeters (1.3 ft).

[36] The tallest recorded tree is one 23 m (75 ft) tall that grows in the Carson National Forest, New Mexico.

[46] They can be encouraged to grow more quickly with supplemental water, but overwatering resulting in deformed growth or death is a frequent problem in landscaping.