The Library of Congress Classification Scheme for Cartographic Materials

- Tsering Wangyal Shawa

The main aim of any classification scheme is to organize the information in a group, so that the organized materials can be found easily by the user. The classifications of books and cartographic materials are different. Books are classified on the basis of subject, whereas the cartographic materials are classified on the basis of area. "It is estimated that ninety-five per cent of map reference requests require searching by area-subject entries. A survey of 360 map libraries in the United States made by a committee of the special Libraries Association, Geography and Map Division, of the United States of America in 1953 revealed that in seventy-two per cent of the libraries, maps were most often requested by area alone, or qualified by date or subject. They were seldom requested by author or by title." Wallis, (1960). The cartographic materials include atlas, globe, maps, views, cross-sections, plans, remote sensing imagery, etc.

Different classification systems such as BOGGS, Dewey Decimal Classification, Universal Decimal Classification, Ministry of Defence (UK), and the American Geographical Society systems have been developed for cartographic materials over the years, however, the Library of Congress classification scheme for cartographic materials is the best classification system. This Classification is based on an alphanumeric system, and it is contained in the Schedule G of the Library of Congress classification system. The Schedule G of the Library of Congress cartographic section is broadly divided into atlases, globes, and maps. Each of these are given blocks of numbers such as G1000.3 - 3122 for atlases, G3160-3182 for globes, and G 3190-9999 for maps. Some blocks of numbers were not assigned and left for future use. This paper will focus on the Library of Congress map classification system, that is, how the maps are classified between the block number G 3190-9999.

The Library of Congress devised the cartographic materials classification system in 1900 and its first edition of the cartographic classification was published in 1910. Since then, four major editions have been published. The cartographic classification is based on an area and hence, it is divided into a hierarchical system. The first category is the universe or the solar system. That is followed by the world map, then by continents, which are further subdivided either by regions and natural features, or by political divisions such as countries. The following is a summary of the Library of Congress classification system for maps.

Universe, solar system			        3190-3192

World						3200-3202

North America					3290-3292

	Canada				        3400-3654

	United States				3700-3702

	By states				3710-4374

South America				        4400-4402

	By country				4410-5663

Europe						5700-5702

	By country				5720-6985

Asia						7400-7402

	By country and area			7405-8192

Africa						8200-8202

	By country and area			8210-8904

Australasia					8960-8959

	By country				8960-9080

Atlantic Ocean					9100-9172

Indian Ocean					9175-9227

Pacific Ocean					9230-9774

Arctic Ocean					9780-9797

Antarctica					9800-9802

Unlocalized maps				9900-9999

The maps of the universe, the world, and the continents are further classified as general maps, thematic maps, and regional or natural features maps. These are assigned different numbers at the end of their classification numbers such as '0' for general maps, '1' for thematic and '2' for regional or natural features.

The thematic maps are further classified on the basis of topics. They are broadly divided into seventeen classes, with a different letter for each group. These groups are further subdivided on the basis of more detailed topics. For example, a Physical Map of North America will be classified as G; 3291 .C2, whereas a Geological Map of North America will be classified as G;3291 .C5. Both of the maps are part of one theme, that is, physical science, however, they are also subdivided by more detailed topics. The thematic classification scheme can be used in conjunction with other subclassifications. Examples of these groups will be discussed later in this paper. Below is a listing of major classifications of thematic maps:

A	Special categories

B	Mathematical geography

C	Physical sciences

D	Biogeography

E	Human and cultural geography. Anthropogeography. Human ecology.

F	Political geography

G	Economic geography

H	Mines and mineral resources

J	Agriculture

K	Forests and forestry

L	Aquatic biological resources

M	Manufacturing and processing. Service industries.

N	Technology. Engineering. Public works.

P	Transportation and communication

Q	Commerce  and trade. Finance

R	Military and naval geography

S	Historical geography

Unlike the maps of the universe, the world, and the continents that are classified into three subgroups, the maps created by political divisions or map of the countries are classified into five subgroups on the basis of their subjects. These subgroups are assigned different numbers at the end of their classified numbers such as:

0 or 5 General maps

1 or 6 Thematic maps

2 or 7 Regions, natural features etc.

3 or 8  Major political division (states, provinces, counties, districts maps)

4 or 9  Cities or towns maps.  

Let us examine how the maps are classified into the above groups. General maps are those maps which are meant for general purposes and cover very general topics. They are given number '0' or '5' after third digit of the classified block number. The maps which depict one particular topic such as military maps, highway maps, or tourist maps are classified as thematic maps. They are classified under number '1' or '6'. The maps featuring river valleys, mountain ranges, deserts, and maps covering three or more political divisions are classified under number '2' or '7'. The major political divisions, such as counties and districts, are classified under number '3' or '8'. The smallest subdivisions of political units, like cities and towns, are grouped under number '4' or '9'.

Classification of maps is not simple; there are many maps which not only cover one political unit, but also cross over other political areas. An example is the map of the Allegheny River. The river is located both in Pennsylvania and in New York State, however, most of the river is located in Pennsylvania and hence, the map will be classified under Pennsylvania. Sometimes a map covers equal parts of two political units, such as a map of the Delaware Bay. This Bay is located equally in Delaware and New Jersey. In a case like this, the map should be classified under whichever area comes first alphabetically and therefore, a map of the Delaware Bay is classified under Delaware state. When a natural feature or other subject in the map covers three or more administrative divisions, it is classified slightly differently. An example is the map showing the Appalachian Mountains. This type of map is classified under larger geographical region, hence the Appalachian Mountains is grouped under Eastern United States(Larsgaard 1987, 87).

The information on a map is not necessarily as simple as the above examples. There are maps which will show more than one type of information, such as the Rainfall Map of Wenatchee National Forest. This type of map is classified first under the state, because the National Forest is located in Washington state (G; 4280), then under the region, because Wenatchee National Forest is one distinct region in Washington state. In this case the classification number will change from G; 4280 to G; 4282 then add its cutter number that is, .W4 so that this map will be classified G; 4282 .W4, under Wenatchee National Forest. The same map is then further classified under topic, in this case rainfall, and hence it is grouped under the rainfall category (in the thematic classification, 'C' stands for Physical sciences and 'C883' represents rainfall). This map will be classified as G; 4282 .W4C883. The rules of the Library of Congress classification state that "a subject cutter may be added after another cutter for political or geographic subdivision (making a total of 3 cutters for the map) but a geographic cutter never follows a subject cutter.

The county, city, and town maps representing various topics will be classified in a similar manner. However, smaller political divisions within major political divisions such as cities or towns are classified slightly differently by the use of the colon followed by the number such as the number '2' for geographic subdivision and the number '3' for a political subdivision. For example, the map showing the location of JFK International Airport will be classified as G; 3804 .N4:2J6. The number G; 3804 is designated for the city or town in the state of New York and '.N4' is the cutter for New York City. Since JFK airport is an important geographical subdivision within New York City ':2' is used after 'N4' in order to differentiate a JFK airport map from other New York City maps. 'J6' is the cutter for JFK International Airport. The Map of Queens (a part of New York City ) could be classified as G; 3804 .N4:3Q4. The ':3' is used after the 'N4' because Queens is one of the political subdivisions of New York City and 'Q4' is the cutter for Queens. A transportation map of Queens could be classified as G; 3804 .N4:3Q4 P1. since the 'P1' stands for transportation under the thematic subclassification (LC Subject Cataloging Division. 1976, 207).

The date of a situation or the date of publication of the map and the cutter for the statement of responsibility are all used in conjunction with the above classification system in order to further classify the maps. Often the date of information or situation is not stated on the map; in such cases the date of publication is used.

While classifying maps, the main class number is always for the main geographic area shown on the map. It can be further subdivided by using cutter numbers first for geographic subareas, and then for the topic content. After the topic content of the map is the date of the situation, and then the cutter for the main entry (the statement of responsibility). For example, "The Geology Map of New York City" published by the United States Geological Survey in 1990 will be classified as G; 3804 .N4C5 1990 U5. In Physical Sciences 'C' section of the thematic classification, the 'C5' stands for geology, '1990' is the year of publication and 'U5' is the cutter for USGS.

Sometime a map is a facsimile or formally published reprint. In a situation like this there will be a second date after the main entry cutter - the date of publication of the reprint. One example is the Map of Ithaca, NY drawn by L. R. Burleigh, first published in 1865 and reproduced in 1970 by Historic Urban Plan, Ithaca. This map will be classified as G;3804 .I7 1865 B8 1970. The 'G; 3804' is the classification number for the city or town in New York state, 'I7' is the cutter number for Ithaca, '1865' is the date of the situation, 'B8' is the cutter for the author and '1970' is the date of reproduction.

The classification of series maps is slightly different from the above system. In the series classification, the date in the call number is replaced by the denominator of the R.F. (Representational Fraction ) scale minus the last three digits, and by a lowercase letter 's'. For example, the series map of New York State with R.F. scale of 1:25,000 and published by the USGS will be classified as G; 3800 s25 U5. Similarly, "The Ethnolinguistics Map of New York State" with R.F. scale of 1:500,000 and published by the Cram Company will be classified as G; 3801 E3 s500 C7. The main difference between the series classification and the rest of the map classification systems is the replacement of the date of situation or the date of publication with the scale.

The Library of Congress Schedule G Classification for maps is not free from weakness. It does not have a good classification scheme for those countries for which the Library of Congress has few maps. It is also weak for countries considered politically insignificant and regions which are not properly mapped. Another weakness is that since the Schedule G classification system is based on area and political boundaries, this results in problems when countries break up into separate political entities. For example, Moscow used to be classified as a city in the Soviet Union (G; 7004 .M6). Now it is no longer classified under the Soviet Union, but under Russia (G; 7064 .M7). This change in classification is due to a change in political boundaries. Another problem concerns the classification of regions. The United States Board on Geographic Names has established geographic names, and the Library of Congress uses this Board as its authority on geographic names. If the Board fails to established regional geographic names in time (it happens quite often), then the Library of Congress is forced to classify the region using an unestablished geographic name. This later complicates the classification system. However, the Library of Congress map classification scheme is the most widely used system in United States academic libraries, and in libraries around the world. This classification scheme is not only the de facto classification system for maps but it is also the best system in the world for the classification of cartographic materials.

  1. Larsgaard, Mary Lynette. Map Librarianship: An Introduction. Second Edition. Littleton, Colorado, Libraries Unlimited, Inc. 1987
  2. Library of Congress, Subject Cataloguing Division. Classification: Class G; Geography, maps, anthropology, recreation 4th ed. Washington, Library of Congress. 1976
  3. Nichols, Harold. Map Librarianship. Second Edition. London, Clive Bingley Ltd. 1982
  4. Parry, R.B. & Perkins, C.R. Information Sources in Cartography. London, Bowker-Suar Ltd. 1990
  5. Wallis, H. "The role of a national map library". Cartographic Journal, V.3, P.11-13, 1966.

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