Dot Density Maps

Dot density maps, or dot maps, portray the geographic distribution of discrete phenomena using an arrangement of identical point symbols, most [Page 788]commonly dots. The dot density technique dates to at least the 19th century and is today accepted as one of the primary techniques for representing geographic patterns. Dot density maps are particularly useful for understanding global distribution of the mapped phenomenon and comparing relative densities of different regions on the map. Dot density maps are also easy to understand, requiring little cognitive effort from the map reader when compared with isoline maps. However, retrieval of specific information from dot density maps is difficult as map users find manual counting of dots tedious and tend to underestimate dot totals as the density increases.