Dewey Decimal Classification

The numeric system employed by the Dewey Decimal Classification (DDC) system can be used to classify maps. Numbers are used to represent the form, the area, and the subject of the map in question. Like the Library of Congress Classification, DDC has a section of the schedule devoted to maps, titled "Graphic representations of surface of earth and of extraterrestrial worlds", with the corresponding base number 912. Geographic area notation is determined from the notations in Table 2, and the topical notations are built from the schedule itself. This part of the schedule is only used for those maps concerning geography, travel and roads. Historical Atlases are classed in 911, "Historical Geography". Any graphic representation that does not fit in the above categories is first classed by subject. Form is added using the miscellaneous section of Table 1, "Maps, plans, diagrams". For example, a Railroad atlas would be classed first under "Railroads".

DDC is a cumbersome system in any situation where a patron may want to access maps both by subject and geographic location. Larsgaard considers Dewey to be the most difficult classification system to apply to maps (Larsgaard, 1987, 96). Alonso and Prescott, however, argue that libraries may find it more convenient to use Dewey than any other classifications system if they have relatively small and homogenous map collections and already use Dewey for print materials, if only because staff are familiar with the system. They also suggest that in this type of situation most patrons seek maps by geographic representation, which makes classification by subject unnecessary (Alonso and Prescott, 1977, 48).

According to Larsgaard, a trend has recently developed whereby more thematic maps are being classified by form within the 912 section. For example, road maps used to be classed in 388.10223, "Roads", but are now often being classed in 912. However, Larsgaard points out that in the case of topographic and geographic maps, many libraries that are using DDC to classify maps often leave off the 912 designation so that the maps are accessible by geographic area rather than by form (Larsgaard, 1987, 135).

Examples
Here is the process by which a Dewey Decimal call number is developed for an Ethnology Map of Illinois, U.S.A:
oooooo1) Indicate "map and atlases" by using base number 912
oooooo2) Note the region, for "Maps of Illinois" (773)
oooooo3) Add table annotations to indicate subject, for "anthropology/ethnology" (572)
oooooo4) Develop call number: 912.773572


"Dewey Decimal Classification" Bibliography

Alonso, P.A.G and D.F. Prescott. "Deweying maps". The Australian Library Journal (March 1977): 47-52.

Larsgaard, Mary Lynette. Map Librarianship: An Introduction. Second Edition. Littleton, Colorado, Libraries Unlimited, Inc. 1987.

 

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