Types of Distribution Maps

Dot Distribution Maps

• A dot map is a distribution map that focuses on a single element in a given area. An example would be a soil distribution map of the United States. As dot maps use dots in an area to show size and frequency, a map like this might show dots representing how often a certain type of soil occurs in a specific area. Other dot maps will use their own dotting system for their particular subject matter.

Thematic Distribution Maps

• Another type of distribution map is a thematic map. Thematic maps focus on a single element in an area by using shading to represent that element. For example, a map of the United States that shows where a particular tree species lives would show an outline of the U.S. with only that area where the tree species lives shaded a different color from the rest of the map.

Statistical Distribution Maps

• Statistical distribution maps are similar to thematic distribution maps in that they use shading to represent their theme. However, a statistical map usually shows where and how often something occurs. These maps use multiple shadings of color to represent their subject. Common examples of statistical distribution maps are population density maps which use different shades to show how large the population is over a given area.

Special Purpose Distribution Maps

• A special purpose distribution map is one that may use one or all of the different techniques used in the types of distribution maps already mentioned -- dot, thematic, and statistical maps. It may also incorporate more than one element in the subject matter it is illustrating. Excellent examples of these types of maps are those generated by the U.S. Census Bureau, which show both a thematic element, like the Hispanic population of the U.S., and a statistical element, such as the population density of the Hispanic population of the U.S.