Billboards are everywhere. In the United States alone, it's estimated that there are approximately 370,000 billboards on local, state and federal roads. Most of these billboards are static. They're displayed in certain areas to reach a company's demographic, but there is no way to tell if the billboards are actually working. A solution to this is digital out of home advertising.  On the whole, the digital outdoor advertising market, which includes posters, billboards and televisions, is set to reach $50.7 billion globally by 2020.