Classed Choropleth Map

http://my.ilstu.edu/~jrcarter/Geo204/Choro/

A classed choropleth map is an aerial map that breaks the colors on the map into a specific and small number, usually four, that give a data range for that area corresponding to the quantity of data in the color key.The map above portrays data for the 50 states and Puerto Rico. The subject is the ratio of the number of males in the population compared to the number of females.