Does Paladine Smite apply to every hit or just the first hit each round?

@JeremyECrawford @mikemearls Paladin's smite spells cast as a bonus action. Does it apply to every hit or just the first hit each round?

— Todd (@fmacanadaguy) April 11, 2016

@fmacanadaguy @JeremyECrawford just the next hit

— Mike Mearls (@mikemearls) April 11, 2016

Wrathful smite, branding smite, and similarly worded smite spells work for one hit only. #DnD https://t.co/NZJOgRTxQY

— Jeremy Crawford (@JeremyECrawford) April 11, 2016