Notwithstanding any other provision of law, the state of New Mexico hereby finds and declares that the removal of certain directional signs, displays and devices, in certain specified areas, lawfully erected under state law in force at the time of their erection, which do not conform to the requirements of Subsection (c) of 23 U.S.C. § 131, which provide directional information about goods and services in the interest of the traveling public, and which were in existence on May 6, 1976, may work a substantial economic hardship in such defined areas.