cartogram

Area cartogram of the United States, with each county rescaled in proportion to its population. Colors refer to the results of the U.S. presidential election, 2004 popular vote.

A cartogram is a map in which area is not preserved. Instead, another thematic mapping variable like travel time or Gross National Product is substituted for land area. In other words, the geometry or space of the map is distorted in order to convey the information of this alternate variable. There are two main types of cartograms: area and distance cartograms.

An area cartogram is sometimes referred to as value-by-area map or an isodemographic map. The latter particularly for a population cartogram, which illustrates the relative sizes of the populations of the countries of the world by scaling the area of each country in proportion to its population; the shape and relative location of each country is retained to as large an extent as possible, but inevitably a large amount of distortion results. Other synonyms in use are anamorphic map or density-equalizing map [1][2]. The German word for cartogram is Kartenanamorphote, and not Kartogramm [3]

A distance cartogram may also be called a central-point cartogram. This form is typically used to show relative travel times and directions from vertices in a network.

Bibliography

• Campbell, John. Map Use and Analysis. New York: McGraw-Hill, 2001.
• Gillard, Quentin. "Places in the News: The Use of Cartograms in Introductory Geography Courses." Journal of Geography. 78 (1979): 114-115.
• Tobler, Waldo. "Thirty-Five Years of Computer Cartograms." Annals of the Association of American Geographers. 94 (2004): 58-73.
• Vescovo, Victor. "The Atlas of World Statistics." Dallas: Caladan Press, 2005.

External links

• Cartogram Central
• Multiple cartograms showing the results of the 2004 US Presidential Election
• Worldmapper collection of world cartograms

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