Source: http://www.nationaljournal.com/2016-elec...

One of the largest chunks is "digital advertising."

The average American spends 11 hours a day on electronic media, including computers and smartphones—and presidential contenders have caught on.

In 2008, Obama spent $21.1 million on digital ads. Only four years later, that more than tripled to $74.5 million—making up 10 percent of his total spending.

If this trend continues, a 2016 presidential candidate could easily spend up to $260 million in this category. Sixteen years ago, former President George W. Bush only spent $120,000.