Cartograms

the concept of relative space was developed in geography and cartography during the 1960s. one of its main devices are cartograms, two dimensional representations of relative space. once again, the parameter that defines distance and space can be completely arbitrary. this map of the U.S., for example, is scaled according how many people in each state attended an elvis concert.

source: http://www.owu.edu/~jbkrygie/krygier_html/geog_353/geog_353_lo/geog_353_lo03.html