Young men put Trump in power? Afraid not. The demographic data shows that if it was narrowed down to one group, it was poorly educated white Christians over the age of 50.
I mean election victories are typically both multicausal and overdetermined. Poorly educated white Christians over the age of 50 form the GOP base, but especially a GOP win in the popular vote requires far more than that.
Parties focus so much on swing voters for a reason, and a lot of these swing voters are in fact swung by what they see online.
