How much is spent online for US Presidential elections?

This presidential election will see 145 percent higher spending than seen during last elections. However of the total $4.5 billion spent on advertising overall, only 1.6% or $73 million will be on the internet.

Of this $73 million, 80 percent shall be towards email spending. Since April, 172 million display ad impressions have been advertised by both Democrats and Republicans hopefuls.