Univariate Choropleth Map

http://www.colocarto.com/custom-thematic-maps.html

A univariate choropleth map is a lot like other choropleth maps except it only displays one variable but still having all the criteria to make it a choropleth map. Its just a simpler map. The map above shows the estimated median household income for 2008 in the United States. The map only displays one variable and uses one shade of color to separate the increases.