Proportional Circle Map

Proportional Circle Maps display data in relation to their size of the circles.  Each map will have a legend that shows the numbers each circle represents.  This particular map is showing the number of foreign born Irish per state in the western U.S.  Each circle, depending on the size represents the amount of Irish in that region or state.

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