Choropleth Map

http://my.ilstu.edu/~jrcarter/Geo204/Choro/Tom/

This is an example of a Choropleth map wich has been "classed".  These maps are a special type of thematic map which uses a graphic variable to show quantitative differences. Choropleth maps portray areal data which is then displayed as colors relating to "classes" of predetermined values. The colors can be differnt shades of the same, or completely different colors. This is data that is not based on a total value. However, it is standardized to some unit. The boundaries in this style of map are defined by units such as census tracts, counties, and states. This map shows percent of persons within a defined area, in this case county, who are Hispanic or Latino. The downside of this mapping type is that it can be misleading depending on what is being measured.

Dot Distribution Map: U.S. Population Density

http://www.census.gov/geo/www/mapGallery/2kpopden.html

This is an example of a dot density map prepared by the U.S. Census Bureau in 2000. These types of maps are used to show the quantity of data or property by placing a dot in a geographic unit for each type of specified data point or property. These are also known as point pattern maps that use nonproportional point symbols. The dots are set to a specific scale or number that does not vary. Here, one dot equals 7,500 people. It shows across the U.S. the areas with greater or lesser population by the concentration of dots within an area.