The tract of land in the States of Montana and Wyoming, lying near the headwaters of the Yellowstone River and described as follows, to wit, commencing at the junction of Gardiner's River, with the Yellowstone River, and running east to the meridian passing ten miles to the eastward of the most eastern point of Yellowstone Lake; thence south along said meridian to the parallel of latitude passing ten miles south of the most southern point of Yellowstone Lake; thence west along said parallel to the meridian passing fifteen miles west of the most western point of Madison Lake; thence north along said meridian to the latitude of the junction of the Yellowstone and Gardiner's Rivers; thence east to the place of beginning, is reserved and withdrawn from settlement, occupancy, or sale under the laws of the United States, and dedicated and set apart as a public park or pleasuring ground for the benefit and enjoyment of the people; and all persons who locate, or settle upon, or occupy any part of the land thus set apart as a public park, except as provided in section 22 of this title, shall be considered trespassers and removed therefrom.
16 USC § 21
Establishment; boundaries; trespassers
through Pub. L. 116-344, except Pub. Ls. 116-260 and 116-283