16 U.S.C. § 37

As a means of providing within township 8 south, ranges 7 and 8 east, and township 9 south, ranges 7, 8, and 9 east, Montana principal meridian, the winter range and winter feed facilities indispensable for the adequate and proper protection, preservation, and propagation of the elk, antelope, and other game animals of the Yellowstone National Park and adjacent lands, the Secretary of the Interior, in his discretion, and subject to the limitation hereinafter prescribed may, and is, authorized to perform the following acts: (a) Accept and deposit in a special fund in the Treasury, and expend for the acquisition of lands as herein authorized, private funds donated for such purpose. (b) Acquire by purchase, or by acceptance of donations or bequests, such lands in private or State ownership within the townships above described as he may deem necessary to carry out the purpose of sections 37 to 40 of this title.