Throughout his campaign, Donald Trump has prided himself on not needing traditional paid television ads. By May, he had spent $18.5 million on advertising — substantially less than Bernie Sanders, Marco Rubio, Jeb Bush, Hillary Clinton and Ted Cruz, slightly less than John Kasich.

As NPR’s headline writers put it, “Sanders has spent the most on ads, but Trump has spent best.” In lieu of a massive ad budget, Trump instead overwhelmed his foes by amassing nearly $2 billion in free media by mid-March.