The grizzly bear, Ursus arctos horribilis, is a powerful subspecies of the brown bear and a recognized symbol of the American wilderness. This massive mammal, distinguished by the prominent hump on its shoulders, once roamed widely across the western half of the continent. Today, the species’ distribution in the contiguous United States is dramatically restricted, confined to isolated pockets in the Northern Rocky Mountains.
States with Established Grizzly Bear Populations
Grizzly bears currently maintain established, reproducing populations across three states: Montana, Wyoming, and Idaho. Their presence is concentrated within designated recovery ecosystems that span these state lines. The two largest and most robust populations reside in the Greater Yellowstone Ecosystem (GYE) and the Northern Continental Divide Ecosystem (NCDE).
The Greater Yellowstone Ecosystem (GYE) covers parts of northwestern Wyoming, eastern Idaho, and southwestern Montana. Recent estimates suggest the GYE population is robust, numbering approximately 965 to 1,069 bears. The Northern Continental Divide Ecosystem (NCDE), centered in north-central Montana and encompassing Glacier National Park, supports the other major concentration. This population has been estimated to number around 765 bears, a figure likely higher now due to continued growth.
Beyond these two major population centers, several smaller recovery zones exist, though they house fewer bears. These zones include:
- The Cabinet-Yaak Ecosystem, located in northwestern Montana and Idaho, supports an estimated 30 to 40 bears.
- The Selkirk Ecosystem in northern Idaho and northeastern Washington maintains a population of about 75 bears.
- The North Cascades Ecosystem in north-central Washington is considered functionally unoccupied, with only occasional sightings.
- The Bitterroot Ecosystem in central Idaho and western Montana currently has no known established population.
The Historic Decline of the Grizzly Bear
The current, limited distribution of the grizzly bear starkly contrasts with its vast historical range across western North America. Before European settlement, an estimated 50,000 grizzly bears lived in the contiguous United States. Their historical domain extended from Mexico north to Alaska and stretched from the Pacific Coast eastward across the Great Plains, encompassing at least 18 western states.
This extensive population began to collapse with the westward expansion of settlement in the 19th century. Unregulated hunting, government-funded bounty programs, and the conversion of vast tracts of land for agriculture and ranching led to a rapid and sustained population decline. Grizzlies were often viewed as a threat to livestock and an obstacle to settlement, resulting in systematic eradication across much of their habitat.
By the 1930s, the species had been eliminated from nearly 98% of its former range in the lower 48 states. The California grizzly was extirpated by the 1920s, and the last confirmed sighting in Colorado occurred in 1979. By 1975, the total population in the contiguous United States had plummeted to between 700 and 800 individuals, surviving primarily in the remote, rugged mountainous areas they occupy today.
Federal Protection and Recovery Zones
The dramatic decline in grizzly bear numbers led to their listing as a “threatened” species under the Endangered Species Act (ESA) in 1975. This federal protection, overseen by the U.S. Fish and Wildlife Service (USFWS), prohibits the unauthorized harm or killing of the animals. The ESA mandates a recovery plan, which established six geographically distinct Grizzly Bear Recovery Zones as the focus of conservation efforts.
The USFWS uses these zones, including the GYE and NCDE, to monitor population health and manage recovery goals. A major goal of the recovery plan is to ensure genetic diversity through population connectivity, which is difficult given the isolated nature of the current bear clusters. The agency recently proposed establishing a single Distinct Population Segment (DPS) across Idaho, Montana, Washington, and Wyoming to clarify protection boundaries.
The USFWS has faced ongoing pressure and litigation over proposals to remove ESA protections from the largest populations, particularly in the GYE and NCDE. While these populations have rebounded significantly, the USFWS has denied petitions for delisting. They maintain that the bears still require federal oversight to ensure long-term viability and connectivity across the ecosystems. Ongoing management efforts also focus on mitigating human-bear conflicts, which remain the primary cause of mortality.