It was becoming obvious that a separate agency was needed to manage the steadily increasing number of American national parks and monuments. By 1914, there were thirty such sites, including Yellowstone. Each was managed separately, resulting in a lack of direction for the system as a whole. There was also a steady flow of visitors clamoring for information and interpretation of these special places.
The National Park Service Act, passed on August 16, 1916, created
the National Park Service and charged the new agency "to conserve
the scenery and the natural and historic objects and the wildlife
therein and to provide for the enjoyment of the same in such manner
and by such means as will leave them unimpaired for the enjoyment
of future generations."