Types of Thematic Maps

Planimetric (highways) Show the locations of a selected number of features very precisely. Exaggerates the sizes of things that are of interest.

Dot Map Uses a dot to represent the occurrence of some variable in order to depict variation in density in a given area.

Point-symbol Uses a symbol to map phenomena that are discrete (in there own unique location with little to no overlap) Often used in middle school textbooks

Proportional-symbol map Uses a symbol, like a circle to show intensity of frequency, where the size of the symbol varies with frequency or the size of the mapped variable

Flowline Map Shows the quantities of something by varying the size of the symbols

Repetitive symbol maps Map language that uses dots or other repetitive symbols can present three logically different ideas, each based on a different form of information. Actual position of things Spatial arrangement of things General Impression of things

Choropleth Maps Maps the level of some variable within predefined regions, like counties, cities, states. Puts variable into classes and depicts each class with different shading patterns or colors. Used with census tracts, population

Cartogram maps Map like object that shows quantities by distorting the sizes of familiar areas. Can offer a form of visual surprise!

Isoline Map Changes in the variable being mapped across a surface by lines that connect equal points of value

Temporal-trend map Shows how geographic patterns change through time.