Note how "Children are more often shorter than adults" is true despite the existence of Sophie Hollins of Southampton and Peter Dinklage the actor. That isn't an insult to children and it isn't arrogance on my part to say that I am likely taller than a child at my 183 cm. It's just that, absent other information, certain population measures are true about certain populations.

Anyway, I am curious as to whether rural counties vs urban counties exhibit the differences he's talking about. I'll go look at the census and Pew surveys and see what it brings up.