Choropleth Map

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

The choropleth map is defined by areas of the map that already have determined units such as states or counties, and then a measurement is given to those areas based on data. For example, in the map above,  the data being depicted are males per 100 females in the 2000 census. The map then established colors to show which states have a higher proportion of males to females and which ones have a lower proportion. As you can see on the map, Alaska and Arizona are a bright red, this indicates that there are 104-107 males per 100 females which is the highest it gets among the fifty states. States like Georgia and Alabama are represented by a very pale yellow which indicates that they have only 89 to 94 males per 100 females.