Map Types

There are four major kinds of maps that we see. They are isopleth, dot-density, proportional symbol, and chloropleth maps.

Chloropleth maps are shaded so that each shaded area represents a range of values.

Isopleth maps show range of quantity, and are not grouped to a predefined region like a state or country. Data ranges with similar values can be drawn in similar colors, or lines can be drawn so the values are shown as higher or lower than the isopline value. Temperature is commonly displayed using this type of map.

Dot-density maps show the geographic distribution of data using an arrangement of identical symbols, usually dots. Cell-phone usage is one popular example of this type of map. 

Proportional symbol maps display sets of data using proportionally sized symbols to illustrate the data. A higher numerical value or range would call for a larger symbol, and vice-versa.