Dulles currently has just over 22,000 parking spots for travelers, half of them in the distant economy lots. His proposed parking deck — which would go in that same location — would accommodate five times as many cars. Without specifics, it’s impossible to know the actual physical scale of the proposed parking deck. “Why should we build the world’s largest parking garage in the world on an airport we just invested $6B to connect to Metro?” But Trump has touted the proximity and convenience of his new parking deck.