introduction 7
tion that shows spatial relationships.” In this book we will not discuss designing sand
paintings or stick charts; I will confine the discussion to flat maps that show spatial
relationships, but I will look at maps for the visually impaired and maps for the com-
puter monitor and the Web in addition to those drawn on paper.
kinds of maps
Since maps can represent anything that has a spatial component, there are hundreds
of possible map types; however, these can be grouped into a few categories. One
categorization is based on map function. These
functional categories are general-
purpose maps,
special-purpose maps, and
thematic maps. As is common, there is not
complete agreement among cartographers about these terms or categories.
General-purpose maps, or
reference maps, as the name suggests, do not emphasize
one type of feature over another. They show a variety of geographic phenomena
(political boundaries, transportation lines, cities, rivers, etc.) and present a general
picture of an area. They are used for reference, planning, and location. Commonly,
the state or regional maps in an atlas are of this type, and topographic maps are often
placed in this category.
Special-purpose maps are created for a very specific type of user. Geologic, soil, and
cadastral maps are included here. Such maps are usually large scale (showing a small
area and much detail), and the user is usually familiar with the subject, if not the
area.
Navigation maps, which include all types of maps created for route finding,
such as aeronautical charts, nautical charts, and road maps, are often included under
the special-purpose heading, although some consider them to be a separate map type
(Figure 1.4). Special-purpose maps tend to be made at agencies or corporations and
by a team of people.
Thematic maps have been called a variety of names (special subject, statistical, dis-
tribution, and data maps), but the term “thematic” is now generally accepted. The-
matic maps normally feature only a single distribution or relationship, and any other
information shown (base data) serves as a spatial background or framework to help
locate the distribution being mapped. Thematic maps may be either qualitative or
quantitative. That is, they show some characteristic or property, such as land use, or
show numerical data, such as temperatures, rainfall, or population (Figure 1.5). In
this book the primary emphasis is on thematic maps although the design principles
apply to all map types.
Thematic maps were first widely used in the 19th century. These maps are com-
monly used in atlases as an adjunct to general maps. Thematic maps are the primary
map
type seen in newspapers, journals, reports, and textbooks.
Purpose
of Thematic Maps
Thematic maps can be made to represent almost any phenomenon, visible or invis-
ible. They can show actual features on the earth, such as rivers, mountains, and
8
MaP Design
roads; conceptual features, such as the earth’s grid or county boundaries; and ideas
and beliefs, such as locational preference or political ideologies.
Whatever the topic, a thematic map is made for one of three broad purposes:
(1) to provide information on what and perhaps how much of something is present in
different places, that is, data storage; or (2) to map the characteristics of a geographic
phenomenon to reveal its spatial order and organization, that is,
visualization; or
(3) to present findings to an audience, that is, communication.
Data storage is a map function that has long been recognized, although the term
