Proportional Circle Map

Proportional circle maps use circles imposed over a geographical area to represent numerical and proportional data. By applying a formula to control the area of the circles, the size of the circle reflects the amount of data over that area. The map below is a proportional circle map showing the Filipino population in the south eastern U.S. in the year 2000. Without even reading the numerical values, it can be easily seen that the largest percentage of Filipinos in the United States live in West Virginia, Florida, and Texas.

http://www.neiu.edu/~ejhowens/377/examples.htm