A cartogram is a map in which a thematic variable replaces land area or distance. This often distorts the area or size of the map. The variable can be anything like income, population, gross national product, etc.
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http://en.wikipedia.org/wiki/File:Cartlinearlarge.png
This cartogram has the counties of the country rescaled to depict population, and it also shows the popular vote during the 2004 elections.