Thematic map of population

http://images.google.com/imgres?imgurl=http://www.lib.wsc.ma.edu/themap.jpg&imgrefurl=http://www.lib.wsc.ma.edu/censusaff.htm&h=381&w=505&sz=36&hl=en&start=2&usg=__hqgN0t4ZzGISnG3TyTMxDe6G_Ak=&tbnid=lfQhH-KYeLkvyM:&tbnh=98&tbnw=130&prev=/images%3Fq%3Dthematic%2Bmaps%26gbv%3D2%26hl%3Den%26sa%3DG

http://www.lib.wsc.ma.edu/themap.jpg

This is a thematic map of the median age of population from state to state in the Northeastern and Midwestern United States. Thematic maps are used for focusing in one one or a few particular geographic distributions. For example, on a normal reference map there may be 10 different breakdowns, while a thematic map may take 1 or 2 of those things and give more detail about them on a map.