As the name suggests, thematic maps show a specific theme or topic. These maps generally show quantitative or qualitative data about an area. These maps focus on the distribution of data based on its location. Thematic maps typically show spatial patterns and can be used to compare datasets. There are four general types of thematic maps:
- Dot density
- Proportional symbol
Dot density maps show points of data where they lie on the ground. Each data point is drawn even if they overlap. The following is a very early example of a dot density map. It's a map made by Dr. Snow to show cases of cholera near Broad Street in London, England in 1854:
Proportional symbol maps show data values ...