16 U.S.C. § 343c-4
The Secretary of the Interior may convey to one Maurice Rich, Senior, a portion of the Acadia National Park, comprising approximately one and eight-tenths acres in the town of Southwest Harbor, Maine, and in exchange therefor the Secretary may accept from said Maurice Rich, Senior, any property which in the Secretary's judgment is suitable for addition to the park. The values of the properties so exchanged either shall be approximately equal, or if they are not approximately equal the values shall be equalized by the payment of cash to the grantor or to the Secretary as the circumstances require. Any cash payment received by the Secretary shall be credited to the land and water conservation fund in the Treasury of the United States. A conveyance of the federally owned lot shall eliminate it from the park.
16 U.S.C. § 343c-4