In our lifetimes, we have witnessed many shifts in ad spending. The switch from analog to digital happened really quickly, but it didn’t stop there. We are now in the midst of mobile advertising taking the social world by storm.

According to eMarketer Chairman Geoff Ramsey, mobile ad spending is expected to make up about 68% of Facebook’s revenue, and 84% of Twitter’s revenue. In the US alone, the three giants – Google, Facebook, and Twitter, earn well over 60% of all money that is spent on mobile advertising. Ramsey estimates that mobile ad spending in the US will surpass $58 billion, and capture 71% of all digital ad spending by 2018.

Why such an increase? Why not?! The level of smartphone ownership amongst target demographics of nearly all brands is downpacked. Over 90% of buying audiences (consumers between ages 12-64) are in possession of a smartphone. As far as social media usage is concerned – comScore reports that over 70% of all time spent on social media occurs over smartphones. The mobile screen has taken center stage, and kicked television screens to the curb.

Okay sure, TV may remain the king of content for a little while longer, but the growth of media spend in the US is being driven by digital and mobile because of usage patterns. The use of mobile even surpassed that of desktops, by an extra 30 minutes each day for each user.

At this rate, it won’t be long for mobile ad spending to overtake desktop (which is already on the decline.)