Maps provide visual representations of geographic information and come in many types for different purposes. They combine elements of art, science, and technology. Atlases collect related maps focused on a subject. Assessing maps considers their scale, projection, currency, and usability. While physical maps are expensive, many free digital maps are available online from commercial and organizational sources. Geographic information systems now process digital data to create interactive maps.

1. Maps
How we visually represent
geographic information
Cartography, the study and
making of maps, goes back
thousands of years and
combines elements of visual
art, science, mathematics,
and modern information
management technologies.

2. Section of the 5th
century Roman map
Tabula
Peutingeriana, a
predecessor of the
modern road map.

3. Types of Maps: different maps answer different kinds of questions
• Road: shows roads, other transit routes, and related points of interest
• Topographic: describes the physical surface shape of an area, typically using
contour lines to depict relief
• Nautical chart: may indicate water depth, tides, currents, and other maritime
features
• Geological: for geological features including strata and faults
• Topological: displays only an abstracted set of information frequently without
regard to scale or distance; commonly used for subway maps and map-based data
visualization applications
• Political: indicates territorial borders; frequently used with road maps
• Historical: describes historical changes in territory, population, and other topics
• And more…

4. Google Maps: political, road, and topographical map

5. Atlases:
collections of related
maps
Typically focused on a
geographic or thematic
subject (i.e. South
America, ecology, The Civil
War, etc.)
Background: title page illustration from Theatrum Orbis Terrarum, sive, Atlas
Novus, an early atlas published in Amsterdam

6. Assessing the Value of a Map
• Scale: How much detail does a map provide? A map with a scale of
1 : 50,000 will have much more information than one with a scale of
1 : 1,000,000.
• Projection: How accurately does represented space on the map
correspond to real life space? Librarians should be aware of how much
distortion there is in a given map as a result of how curved surfaces are
rendered in two dimensions.
• Currency: For maps without historical value, how recently were they
updated?
• Usability: How effective is a given format? Does a digital resource
have a confusing user interface, or is an atlas well indexed?

7. Physical maps can be very expensive, as well as difficult
to store and maintain. However, libraries of all sizes can
benefit from the many maps that are available for free
on the Internet.
Claudius Ptolemaeus (above) did not have access to the World Wide Web

8. Most common are the commercial sources that specialize in
current, comprehensive maps, which work very well for
directional or distance-related questions. They also offer
aerial views and a growing number of new features.
• Bing Maps
• MapQuest
• Google Maps/Google Earth
• Yahoo! Maps

9. Some organizations have digitized their collections
of rare and historically significant maps
• Library of Congress: the maps of the vast American Memory
collection memory.loc.gov/ammem/gmdhtml/
• Old Maps Online: a brilliant portal that links to collections
around the world www.oldmapsonline.org/
• Map History: links to digital collections, great for early maps
www.maphistory.info
• David Rumsey Collection: focused on rare 18th and 19th
century North American and South American maps
www.davidrumsey.com

10. Geographic Information Systems: the Future of Maps
A GIS is capable of processing digital data and presenting it as
something that we would recognize as a map
These websites combine census
and demographic information
with mapping tools :
National Historical Geographic
Information System
www.nhgis.org
Social Explorer
www.socialexplorer.com