Oh, Lizelle! What a seriously good article. That is just beauty.
I'm no cartographer but I do love maps of all sorts. I have a two maps of the US on my living room walls. One is the official USHighway department map of the Scenic Byways in the US and the other is shaded by using road density. It's a bit different than a population map would be.
The two sources you provided alone were worth more than the price of admission! Thank you!