Cartogram

http://amphibiaweb.org/amphibian/cartograms/

Above is a Cartogram, it is a thematic mapping technique that shows a distinguished variable such as population, time change, gross national product and more.  Certain areas of the map are distorted in order to depict information of the alternative variable that is available.  The main two types of cartograms are either distance or area, these maps are historic in the sense they have been being used since the 1800s.