This is a map showing the beer vs wine preference across American counties. The brightness is based on how much we spend on beer and wine.
Visit this story map to walk through the process and rationale leading up to this value-by-alpha map, if you dare!
After sharing this map, a fellow map nerd helpfully pointed out that the color gradient I used tended to bias towards wine. And I think he’s right. The neutral value (spends the same on beer and wine) was a pinkish color -the interpolated hue between the amber beer color on one end, and the purplish wine color on the other. So, here is the same map, with that middle color desaturated to gray.
Now the story of wine-favoring counties being few but fanatically so really shines.
This is one of the adventures in mapping. You are only done with a map to the extent that you choose. And I dig that.
Adventures In Mapping 