Wikipedia - Out-of-home advertising

Out of home advertising is focused on marketing to consumers when they are "on the go" in public places, in transit, waiting (such as in a medical office), and/or in specific commercial locations (such as in a retail venue). OOH advertising formats fall into four main categories: billboards, street furniture, transit, and alternative.
Traditional roadside billboards remain the predominant form of OOH advertising in the US with 66 percent of total annual revenue. Today, billboard revenue is 73 percent local ads, 18 percent national ads, and 9 percent public service ads.
https://en.wikipedia.org/wiki/Out-of-home_advertising