Unclassed Choropleth Map

Unclassed Choropleth Maps do not use ranges or classes to determine color shading. Instead it goes from lightest to darkest shade and has a lowest and highest number. There is one range and the variable is shaded according to where it falls on the shading scale. This type of map is similar to the Continuously Variable Proportional Circle Maps but it uses shading, colors, and patterns of aerial units versus varying circle sizes.

The map shown is an Unclassed Choropleth Map of "Population Density" of people per square km. It is an Unclassed map because the shading varies on the number of people per square mile not a range of people per square mile.

http://visibleearth.nasa.gov/view_rec.php?id=116