The control of signs in areas adjacent to the highways of this state is declared to be necessary to protect the public investment in the state highways; to attract visitors to this state by conserving the natural beauty of the state; to preserve and promote the recreational value of public travel; to assure that information in the specific interest of the traveling public is presented safely and aesthetically; to enhance the economic well-being of the state by promoting tourist-oriented businesses, such as public accommodations, vehicle services, attractions, campgrounds, parks, and recreational areas; and to promote points of scenic, historic, cultural, and educational interest.