Mobile-Ad Spending Leaps, but Trails User Growth

After less than a decade of existence, smartphones and tablets in 2014 will draw more money from advertisers than the centuries-old newspaper industry or the nearly century-old radio sector, a sign of just how rapidly technology is transforming media habits.

But given how much time Americans spend on their devices, mobile-ad spending could be much higher, an indication that marketers remain uncertain about the medium's effectiveness. Research firm eMarketer estimates that spending on mobile advertising, which includes both smartphones and tablets, will soar 83% to nearly $18 billion in 2014. Newspapers will draw nearly $17 billion, while radio will bring in $15.5 billion.

Still, the imbalance remains stark: American adults now spend almost a quarter of their media time on mobile devices, eMarketer estimates, yet 2014 spending growth will raise mobile's share of the ad market to only 9.8%. By contrast, American adults spend only 2% of their media time reading newspapers but ad spending for the sector hangs just under 10% of the overall market, eMarketer estimates.