(1) To promote the safety, convenience, and enjoyment of public travel and the free flow of interstate commerce and to protect the public investment in the National System of Interstate and Defense Highways, hereinafter called the Interstate System, it is in the public interest to encourage and assist the States to control the use of and to improve areas adjacent to such system by controlling the erection and maintenance of outdoor advertising signs, displays, and devices adjacent to that system.

(2) It is a national policy that the erection and maintenance of outdoor advertising signs, displays, or devices within 660 feet of the edge of the right-of-way and visible from the main-traveled way of all portions of the Interstate System constructed upon any part of right-of-way, the entire width of which is acquired subsequent to July 1, 1956, should be regulated, consistent with national standards to be prepared and promulgated by the Secretary of Transportation.