Denali National Park and Preserve was originally created in 1917—five years after Alaska became a U.S. territory, but 45 years before Alaska became a state—to preserve Dall sheep from over-hunting. Dall sheep, a subspecies of the more well-known Ovis aries, is found only in Alaska and western Canada, where they inhabit some of most rugged alpine areas. In 1906, Sheldon came to Alaska to study Dall sheep populations and collect specimens for study and display. Unlike the rest of Interior Alaska, Dall sheep have been barely affected by mankind and our harvest cycles, which was of unique interest to Sheldon. Additionally, conservationists and wildlife managers (like Sheldon) were particularly interested in the species because it is one of the few populations in North America that is not hunted, yet still shares its habitat with a number of large predators—grizzly bears included. In short, Sheldon persuaded Congress to create (what was then known as) Mount McKinley National Park to facilitate the continued study of his sheep and the other species that encompass the "Big Five" on Alaska's Interior.