GEOG 486
Cartography and Visualization

Part I: Types of Maps


There are three broad categories of maps. The first, reference maps, generally show several types of spatial data without specific emphasis on one type over another. Reference maps can vary in their complexity and size, but generally include just the various geographic features that give a picture of the area being mapped, e.g. political boundaries, cities, topographic features and/or transportation routes. For instance, in the reference map of Thailand below, major cities, roads, railways, rivers and country borders are shown and differentiated by symbol and label, but the map is not made explicitly for navigation or exploration of those features.

A reference map of Thailand showing political boundaries, cities, rivers and roadways.
Figure 1.1.1 Reference map of Thailand.
Credit: Courtesy of CIA

A second type of map is the thematic map, which as its name suggests, means the map has a specific theme or focus. This group of maps is extremely diverse. Thematic maps can vary in topic, complexity, purpose and kind of representation. They generally show characteristics, or attributes, of features that vary spatially. The attribute can vary in a qualitative or nominal way, e.g. categories of land cover; or the attribute can vary in a quantitative way, e.g. amount of precipitation. Thematic maps can represent data with points, lines, areas or volumes. Using visual variables (e.g. hue, lightness, pattern, shape) that fit logically with both the kind of feature being used for the symbols (e.g. point, line, area) and the way the attribute varies (qualitatively or quantitatively) is key to representing data in thematic maps. We will discuss symbolization in more depth in Lesson Two.

A 1974 vegetation map of Thailand on left, and a population map on the right
Figures 1.1.2 and 1.1.3 Thematic maps of Thailand. On the left is a categorical thematic map showing nominal classes of vegetation in 1974, and on the right is a quantitative thematic map showing ordinal classes of population density in 1974.
Credit: Courtesy of University of Texas

Special-purpose maps are a third category of maps. They lie somewhat between reference maps and thematic maps as they are often reference-like in their use but are made for specific types of users or pertain to a specific type of data. Navigational maps, like those in road atlases or nautical/aeronautic charts, are considered special-purpose maps, as are maps for certain industries or occupations, like Sanborn maps, soil maps, and municipal utility maps.

Navigational special-purpose maps for the Appalachian Trail and Porte des Morts Passage
Figures 1.1.4 and 1.1.5 Navigational special-purpose maps. On the left is a portion of an Appalachian Trail map. The full PDF version of the map is available here: On the right is a detail portion of NOAA Chart # 14909 showing ''Porte des Morts Passage'' and Washington Island, Wisconsin.
Credit: Appalachian Trail map courtesy of the National Park Service. Nautical chart courtesy of NOAA
2 examples of special purpose maps, On the left is a Sanborn map, and on the right is a map of the city of El Cajon, CA
Figures 1.1.6 and 1.1.7 Special-purpose maps. On the left is a Sanborn map from 1916 of the area around Indiana's state capitol building. Historically Sanborn maps were created to assess fire insurance liabilities; today they are often used in historical urban research. Full resolution image available here: Indianapolis Baist Atlas Plan # 2, 1916. On the right is a map of the sewer system of the City of El Cajon, CA. Full resolution image available here on page 112:
Credit: Sanborn map courtesy of IUPUI University Library. Sewer system map courtesy of Esri and Tim Williams, Kimberly D. Dodson, and Desiree Taylor.

Recommended Readings

If you are interested in investigating this subject further, I recommend the following:

  • Brewer, C. A. (2008). Designed Maps: A Sourcebook for GIS Users. Redlands, CA: Esri Press