The map lends itself well to analysis. In some cases, Taylor notes, "whole states and even entire regions of the country uniformly support a single team" (looking pretty orange there, Wyoming); in others, individual states are divided against themselves (see Florida). But things get really interesting come playoff season.
Nationwide allegiances shift dramatically when you remove non-playoff teams. By early January, for example, Bronco Country had more than doubled in size. Texas, once a nearly solid greyish-purple monster, was suddenly a heterogeneous mixture of red, purple, orange and grey. See the maps here.
As the post-season progresses, you can see blocks of patchwork in the quilt of American fandom swapped out en masse. Vikings fans don massive cheese hats. The states formerly comprising Bronco Country now root for anybody but Baltimore.
"With only two teams left for the Super Bowl we see a country divided more or less by geography," writes Taylor, "with 49ers fans dominating the West and the Ravens being the most popular in counties in the mid-Atlantic and Southern states. Shown here are all the maps, in order, as the post season progresses.