The grizzly bear (Ursus horriblis) formerly ranged over much of
North America from the mid-plains westward to California and
from central Mexico north to Canada and Alaska . During the
early 1880s there were approximately 50,000 grizzlies in the
lower 48 states . Between 1850 and 1920 the species was
extirpated from 95% of its continental U.S. range . In 1922, 37
populations remained , declining to six by 1975 when grizzly
bear was listed as “threatened” under the federal Endangered
Species Act in the conterminous U.S. . At the time of listing,
fewer than 1,000 grizzlies remained in about two percent of the
species' historic range . Early declines in grizzly populations
were largely a result of persecution by European settlers;
grizzly bears were shot, poisoned, and trapped wherever they
were found . Despite protection under the Endangered Species
Act, human-caused mortality, largely that resulting from human
bear conflicts, has remained the biggest threat to grizzlies .
Approximately 88% of U.S. grizzly bear