23 U.S. Code § 317. Appropriation for highway purposes of lands or interests in lands owned by the United States
If the Secretary determines that any part of the lands or interests in lands owned by the United States is reasonably necessary for the right-of-way of any highway, or as a source of materials for the construction or maintenance of any such highway adjacent to such lands or interests in lands, the Secretary shall file with the Secretary of the Department supervising the administration of such lands or interests in lands a map showing the portion of such lands or interests in lands which it is desired to appropriate.
If within a period of four months after such filing, the Secretary of such Department shall not have certified to the Secretary that the proposed appropriation of such land or material is contrary to the public interest or inconsistent with the purposes for which such land or materials have been reserved, or shall have agreed to the appropriation and transfer under conditions which he deems necessary for the adequate protection and utilization of the reserve, then such land and materials may be appropriated and transferred to the State transportation department, or its nominee, for such purposes and subject to the conditions so specified.
If at any time the need for any such lands or materials for such purposes shall no longer exist, notice of the fact shall be given by the State transportation department to the Secretary and such lands or materials shall immediately revert to the control of the Secretary of the Department from which they had been appropriated.