Outdoor advertising, one of the oldest forms of advertising, is reinventing itself. The $23 billion industry is introducing digital technology to change ads faster, new ways of measuring viewers, and billboards that beam information to cellphones. As a result, outdoor advertising companies — which provide billboards, posters and video screens in public places — are now seeing bigger gains than many competitors.
Because outdoor advertising is much less expensive than TV spots, it still accounts for a smaller part of overall ad spending. But it has become the second-fastest growing form of advertising, behind the Internet, according to market-research and media-buying firms.