Unclassed Choropleth Map

For these kinds of maps the data does not have to be classified. In this certain map they are depicting vegetables harvested for sale in 2002 across the United States.

http://www.nass.usda.gov/research/atlas02/Crops/Vegetables%20and%20Melons%20Harvested/Vegetables,%20Acres%20Harvested%20for%20Sale-choropleth%20map.gif