16 U.S. Code § 145 - Exchange of lands
In cases in which a tract covered by an unperfected bona fide claim or by a patent is included within the limits of this park, the settler or owner thereof may, if he desires to do so, relinquish the tract to the Government and secure other land, outside of the park, in accordance with the provisions of the law relating to the subject of such relinquishment of lands in national forests in the State of South Dakota.
Source(Jan. 9, 1903, ch. 63, § 5,32 Stat. 766.)