Cartograms

http://en.wikipedia.org/wiki/Cartogram

The above map is an example of a cartogram in which the normal standard of measurement for distance or area is replaced by another unit of measurement. They also show quantitative differences by changing the size of geographic norms according to the proportion of the geographic units property. There are two types of cartograms. One stretches and distorts its boundaries while the other type scales the boundaries of each unit according to its rank with others. The map above is an area cartogram of the U.S. where each state is scaled according to its population. The colors (shading) in the map measure the number or percent of democrats and republicans nationwide.



Flow Map: U.S. and China imports and exports

http://www.improving-visualisation.org/vis/id=206

The above map is an example of a flow map. These maps are designed to show the path of entities across a surface and it intensity. The paths in this map are highly idealized meaning it only shows the direction of interaction and not the actual path. This type of flow map is called a desire line map. These maps usually illustrate social or economic exchange using connection points of origin and destination. The above example shows the imports and exports from and to both the U.S. and China. This map also uses proportional circles to display data about a cities import value.









Isoline Map

http://sio.midco.net/dansmapstamps/isoline.htm

This is an example of a Isoline map which uses contour lines (isolines) to represent a third variable. It is a type of hypsometric map where the contours are imaginary lines that join equal point values. This is also a topographic (terrestrial elevation map)  which uses the contour lines to show the shape and elevation of the land. By reading the lines a map reader can determine locations of valleys, hills and cliffs to name a few. 

Proportional Circle Map

http://www.neiu.edu/~tpoconno/geography/377/377home.htm

This is an example of a proportional circle map which uses graduated point symbols. The symbols in this case are circles which uses circle size to portray magnitude. The points are positioned near the center of each area and the size of the point represents the magnitude of the data or phenomena being measured. Here is a map created by the U.S. Census Berueau in 1990 to show the number of homes built before 1940 in each state illustrated.