Choropleth Map

 

http://www.agcensus.usda.gov/Publications/2002/Ag_Atlas_Maps/Crops_and_Plants/index.asp

Choropleth maps are one of the most common types of maps. They use color or shading to represent statistical data for different geographical regions. This map uses shades of green to show the acreage used to grow soybeans on in the US in 2002.