Unclassed Choropleth Map

http://vis4.net/blog/posts/choropleth-maps/

Unclassed choropleth maps are simply a choropleth map that has no key which tells you what the different shades or coloring means. Choropleth maps are used to show many different types of data, because of how useful they can depict differences in data. So the map above can show you differences in states, but not what the variable is.