Univariate Choropleth Map: Annual Income

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

Unvariated choropleth maps depict data from one variable. Although it is shown over a variation it is still referencing one piece of information spanning over a specific region. In this map the annual income per household in the United States in 2008 is shown. As the annual income increases the color darkens.