You're an evil person for throwing out a challenge like that to a map/demography nerd :). A little trip to http://en.wikipedia.org/wiki/List_of_United_States_metropoli... and a little spreadsheet gives 75 million if you only count LA/SF/San Diego in CA, or 85 million if you count all of CA. That's 25-30% of the US population, hardly most.

Now if you were to count GDP of those metro's, I'm guessing you'd be around 50% or more of the country.