The Northern Rocky Mountains gray wolf (Canis lupus pop.) historically occurred throughout Idaho, the eastern third of Washington and Oregon, all but the northeastern third of Montana, the northern two-thirds of Wyoming, and the Black Hills of South Dakota . As early American settlers began moving west, populations of the gray wolf’s important prey species were over-hunted, causing the wolves to resort to hunting sheep and cattle. As a result, the bounty hunting of wolves began in the 19th century and continued through as late as 1965. Around the turn of the century some population control measures were attempted in Yellowstone National Park which led to increased numbers of gray wolves in the area. In response, however, people began killing large numbers of wolves . Beginning in 1912 a minimum of 136 wolves and 80 pups were killed each year and by 1920, only 30-40 wolves persisted in this area . By 1973 gray wolves were exterminated from the western lower 48 states and existed only in northeastern Minnesota and Isle Royal, Michigan .
Protection of gray wolves was not initiated until the enactment of the 1973 Endangered Species Act. By this time gray wolves no longer occurred in the western United States except for the occasional dispersion of Canadian animals into Montana and Idaho that failed to survive long enough to reproduce . Successful recolonization of gray wolves into the Rocky Mountain region did not occur until the early 1980s. Around this time, the Rocky Mountain Gray Wolf Recovery Team was organized with the intent of developing standard observation methods for studying and monitoring the wolves. In 1987, a recovery plan was published. Around this time, the status of the Rocky Mountain Gray wolf was still quite precarious. In Montana, from 1985 to 1986 roughly 15-20 wolves were believed to occur near Glacier National Park; in Wyoming, from 1982-1985 15 wolves were reported at Yellowstone National Park, and the same number were believed to occur in Idaho in 1986 .
Regular monitoring of the Rocky Mountain gray wolf population did not occur until 1995, at which time there were an estimated 14 wolves in Montana and 15 in greater Yellowstone. By 2000, there were an estimated 65 wolves in Montana, 118 in Yellowstone, and 141 in central Idaho . In 2004, a recovery update of the Rocky Mountain gray wolf was released, providing information regarding the status the Gray wolf at three recovery areas: the Northwestern Montana Recovery Area (NWMT) in Montana and the Northern Idaho panhandle, the Greater Yellowstone Area (GYA), which includes Wyoming and adjacent parts of Idaho and Montana, and the Central Idaho (CID) area covering central Idaho and adjacent parts of southwest Montana. As of 2004, 16 packs containing 59 wolves were documented at NWMT . In the GYA, 171 wolves in 16 packs inhabited the Wyoming portion and 17 packs occurred in the Montana region. In the CID 64 wolves in 40 groups and as individuals were monitored . The total population of free ranging Rocky Mountain Gray wolves in each state for 2004 was estimated at 59 in Montana, 324 in Greater Yellowstone, and 422 in Central Idaho. In 2005 population estimates were 93, 294, and 525 respectively .
On February 2, 2006, the USFWS announced their intent to designate the Rocky Mountain population of gray wolves as a distinct population segment and then remove it from the list of endangered species .
 U. S. Fish and Wildlife Service. 1987. Northern Rocky Mountain Wolf Recovery Plan. U.S. Fish and Wildlife Service. Denver, CO. 119pp
 U. S. Fish and Wildlife Service. 2004. Gray Wolf. U.S. Fish and Wildlife Service. Revised May, 2004.
 U.S. Fish and Wildlife Service, Nez Perce Tribe, National Park Service, Montana Fish, Wildlife and Parks, Idaho Fish and Game, and USDA Wildlife Services. 2005. Rocky Mountain Wolf Recovery 2004 Annual Report. USFWS, Helena, MT. 72pp. Available at <http://westerngraywolf.fws.gov/annualreports.htm>
 International Wolf Center. 2005. Gray Wolf Population Trends in the Contiguous United States. Available at <www.wolf.org> updated September 2005.
 U.S. Fish and Wildlife Service. 2006. Designating the Northern Rocky Mountain Population of Gray Wolf as a Distinct Population Segment; Removing the Northern Rocky Mountain Distinct Population Segment of Gray Wolf From the Federal List of Endangered and Threatened Wildlife. Federal Register, February 8, 2006 (71 FR 6634-6660).