Nominal Area Choropleth

source: http://politicalmaps.org/maps-of-the-2008-us-presidential-election/

Nominal area choropleth maps differentiate information based on a quality or name. So in the case of the map above, each state is either assigned the value of "Obama" or "McCain" and the reader can see which states' electoral college voted for Obaama (in blue) or McCain (in red).