There are some nice graphs and maps in the piece —I copied a couple below,— but what I'd like to call your attention to is the section at the bottom, which links to sources, discusses the methodology they employed in a lot of detail, and discloses limitations.
If, as Nate Silver has suggested in articles and recent tweets, journalism is to become a bit more empirical, increasing transparency and accountability by adding methodology sections to stories, rather than relegating them to sidebars or external pages that few readers visit, is a good first step. I know, I know, other publications —FiveThirtyEight itself, ProPublica, and the like— are already doing it, but I wish it'll become standard practice in all news media.