History of wolves in Yellowstone

The history of wolves in Yellowstone includes the extirpation, absence and reintroduction of wild populations of the gray wolf (Canis lupus) to Yellowstone National Park and the Greater Yellowstone Ecosystem. When the park was created in 1872, wolf populations were already in decline in Montana, Wyoming and Idaho.^{[not verified in body]} The creation of the national park did not provide protection for wolves or other predators, and government predator control programs in the first decades of the 1900s essentially helped eliminate the gray wolf from Yellowstone. The last wolves were killed in Yellowstone in 1926. After that, sporadic reports of wolves still occurred, but scientists confirmed in the mid-1900s that sustainable gray wolf populations had been extirpated and were absent from Yellowstone as well as 48 states.^[1]

Beginning in the 1940s, park managers, biologists, conservationists, and environmentalists began what would ultimately turn into a campaign to reintroduce the gray wolf into Yellowstone National Park. When the Endangered Species Act of 1973 was passed, the road to legal reintroduction was made clear. In 1995, gray wolves were reintroduced into Yellowstone in the Lamar Valley. The reintroduction of wolves in Yellowstone has long been controversial, as have wolf reintroductions worldwide.