MapsHow 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.

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

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…

Google Maps: political, road, and topographical map

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

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?

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

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

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

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 Explorerwww.socialexplorer.com