Yellowstone National Park was created by an act of Congress in 1872 to preserve the "Natural Curiosities or Wonders" and to prohibit "Wanton Destruction" of its fish and game. During this time, hunters were shooting thousands of elk and other ungulates (mammals having hooves). To obtain pelts, hunters poisoned the ungulate carcasses to kill wolves and wolverines.

In 1914 the war against predators in the west began as Congress appropriated funds for "destroying wolves, prairie dogs, and other animals injurious to agriculture and animal husbandry" on public lands. This essentially gave the go ahead to exterminate the wolf population and eventually nearly wipe out the natural ecosystem in the west.

In 1926 two wolf pups were trapped on a bison carcass and were the last of over 130 wolves in Yellowstone National Park to be killed during the campaign of 1914. As a result the campaign ended in 1935 and a new National Park Service policy was produced.

Aldo Leopold, a noted biologist, advocated wolf restoration to the Yellowstone ecosystem and other large western wild areas in 1944. This begins an era of nature conservancy to protect what was so nearly wiped out. In 1968 Douglas Pimlott advocated reintroducing wolves to Yellowstone National Park and other parks in Canada.

President Nixon banned the use of poisons on public lands in 1972 and the Environmental Protection Agency (EPA) extended this to private lands. A year later the Endangered Species Act was enacted to mandate a recovery planning for endangered and threatened species. Consequently the Rocky Mountain Gray Wolf was listed as endangered. For the next several years the Gray Wolf was the topic of reintroduction by several biologists and conservationists.

Today there is a major controversy surrounding the reintroduction of the Gray Wolves to Yellowstone National Park. Just in the last five years an Environmental Impact Statement (EIS) was drawn up to list alternatives and their impacts of reintroducing the wolves to Yellowstone National Park and Central Idaho. In October of 1994, the Fish and Wildlife Service proposed starting the reintroduction. This met opposition from ranchers who have lived in this area for many years with no wolves. They didn't know how to cope with these "ruthless killers".