According to at least one report, the days of mobile search being overshadowed by desktop users may be coming to an end. The digital research firm eMarketer projects that the majority of U.S. search ad spending will be directed toward mobile platforms — smartphones and tablets — for the first time in history.

The percentage of paid search moving to mobile platforms will only increase, according to the report. While mobile search made up just 24.7% of search spend in 2013, that number increased to 38.1% this year and is expected to reach 50.1% in 2015. The report also estimates that mobile search spend will reach $12.85 billion next year.

The projections see a steady increase in mobile search spend even after overtaking desktop search. By 2018, eMarketer estimates that more than three-quarters of all search spend will go towards mobile ads, a total representing $25.69 billion of revenue. Despite this continuing trend, both Google and Bing have removed the capability for marketers to distinguish between mobile and desktop search when creating and bidding on campaigns.

Though the mobile spend number includes both smartphones and tablets, eMarketer says that the vast majority of projected increases are driven purely by smartphone search.

So what does this mean for marketers?

Some industries will not — and should not — direct their marketing efforts at mobile users. But many businesses, particularly those in convenience industries like food or retail, need to write ad copy as though all of it will be seen on mobile. Because you can no longer change ad copy or bidding strategy based on the user’s device, focus on where the majority of searches are coming from. For those with a majority of mobile traffic, that means shorter copy and heavy utilization of ad extensions like map and phone number links.