National Billboard Day is celebrated annually on June 1 to honor the significance of billboards as a form of advertising. Created by Keystone Outdoor Advertising, this day recognizes billboards' role in conveying messages to millions of people daily, especially in high-traffic areas. The concept of billboard advertising dates back to ancient times, with modern practices evolving from flyposting in the late 15th century. The establishment of the International Bill Posters Association of North America in 1872 helped structure billboard advertising, ensuring better service for both the public and advertisers. On this day, industry professionals and businesses are encouraged to share how billboards have positively impacted their operations or helped disseminate important public service announcements. National Billboard Day highlights the enduring relevance of billboards in contemporary communication.