Choropleth Map

Choropleth map -  Provides an easy visualization of data measurement across a geographic region.

http://www.agcensus.usda.gov/Publications/2002/Ag_Atlas_Maps/Crops_and_Plants/index.asp - map #02-M259
http://www.nass.usda.gov/research/atlas02/Crops/Fruits,%20Tree%20Nuts,%20Berries,%20Nursery%20and%20Greenhouse%20Crops/Total%20Acres%20of%20Land%20in%20Orchards-choropleth%20map.gif
The above map displays total acres that were orchards in the US in 2002