Introduction
Understanding the IMPORTANCE of the FOURTH digit
The Remainder of the Call Number
Examples and Explanations
G Schedule Lists

The Map Room at the Arthur Lakes Library uses the Library of Congress's "G" Schedule to classify and organize its maps. This Schedule is used by most academic institutions in the United States. The following explanation is meant to let Library users to have a  better understand the "G" Schedule. The "G" Schedule should not be used as a primary reference tool to find maps, but more as a browsing tool.  Since 99.9% of all maps are cataloged, patrons should use the Library's on-line catalog, Catalyst for primary research. There are over 15,000 different "stem" numbers in the "G" schedule. Also many  subdivisions and classifications exist within the "G" Schedule. If you need help understanding the Library's classification systems, PLEASE ASK. WE ARE HERE TO HELP YOU.

While the call numbers on maps may seem confusing or even random, they do follow a logical order. By understanding the scheme by which the maps are classified, you can speed your searches of the Arthur Lakes Library Map Room, as well as other libraries.

The Library of Congress assigns a particular four-digit number to every geographical area. For example: 7820 is China, 5330 is Chile, 4160 is Missouri. When used as a call number, it is always preceded by the capital letter "G" (hence the name "G" Schedule) and are ALWAYS placed at the beginning of a call number. These are some examples of real call numbers in the Map Room: G4310 1954 .U5 (a map of Colorado), G3200 1994 .N3 (a map of the world), G8960 1974 .N3 (a map of Australia).

The fourth digit in the geographical classification number tells you what area of a particular country or state is being covered.

Map classification numbers ending in "0" or "5" cover the entire country or state and have no subject matter--they are only base maps (e.g., 3710, 6980, 4965).

Map classification numbers ending in "1" or "6" cover a large portion of or the entire country or state, AND show a certain subject, like soils, population, or roads (e.g., 3451.J3, 6571.E2, 9206.P2). These subject designations are made up of a capital letter followed by a number or series of numbers. These are placed after the geographical designation. Notice that a "." is placed between the classification number and the subject designation.

Map classification numbers ending in "2" or "7" are followed by a ".", a capital letter and a number or series of numbers. These maps cover a defined region of a country or state, like Rocky Mountain National Park (4312.R6), or the Rhine River (5702.R5), or the Suez Canal (8302.S9). These maps may also show subject--the subjects are designated by the same combinations used in maps ending "1" or "6", but no EXTRA "." is used (e.g. 4312.R6C5, 5702.R5P53, 8302.S9P5).

Map classification numbers ending in "3" or "8" are followed by a ".", a capital letter and a number or series of numbers. These maps cover a county or official zone or district, like Adams County, Colorado (4313.A2), or Normandy, France (5833.N7), or the Toscana Region of Italy (6713.T6). These maps may also show subjects in the same fashion that maps ending in "2" or "7" do.

Map classification numbers ending in "4" or "9" are followed by a ".", a capital letter and a number or series of numbers. These maps cover cities, like Boston (3764.B6), or Tokyo (7964.T6), or Sydney (8964.S9). These maps may also show subjects in the same fashion that maps ending in "2" or "7" do.

The rest of the numbers in a call number designate the map's date or scale, and its author.

The date is placed directly after the geographical and subject designation. Often this date will be incomplete and look something like this: 197-, or 19--. The "-"s mean that the librarian was unable to accurately determine the date the map was made. "197-" means that the map was made sometime during the 1970's. "19--" means the map was made sometime during the 1900's.

Often a date will not be given on a map. Instead, there will be a small "s" followed by a number or series of numbers (e.g., s24, s5000). This means that this map is part of a set of maps covering a particular area. The "s" means "scale". The number is the scale in thousands. For example, "s24" means that a map is at a scale of 1:24,000. "s5000" means that a map is at a scale of 1:5,000,000.

The final element in a call number designates the author of the map. This is usually started with ".", followed by a capital letter, and finished with a number or series of numbers. These letters are assigned via a specific scheme. They help libraries and patrons file and locate maps. The author's element is not essential to the map's subject; just remember that these elements file decimally (so .A47 files before .A8).

G3490 1963 .C3

"G3490" = Saskatchewan without a subject, made in 1963, author's name begins with a "C".

G4800 s250 .U52 ND 15-4

"G4800" = Central America without a subject, "s250" = scale of 1:250,000, author's name begins with a "U", sheet "ND 154".

G4041.C5 1931 .K3

"G4041" = Texas with a subject, "C5" = geology, made in 1931, author's name begins with a "K".

G7621.C5 s100 .I7

"G7621" = Iran with a subject, "C5" = geology, "s100" = scale of 1:100,000, author's name begins with an "I".

G4342.A68 1974 .U5

"G4342" = a part or region of Utah, "A68" = Arches National Park, made in 1974, author's name begins with a "U".

G4262.Y4C5 1989 .T39

"G4262" = a part or region of Wyoming, "Y4" = Yellowstone National Park, "C5" = geology, made in 1989, author's last name begins with a "T".

G4313.J4 197- .M3

"G4313" = a county or province of Colorado, "J4" Jefferson County, made in the 1970's, author's name begins with a "M".

G4313.C4H2 18-- .I3

"G4313" = a county or province of Colorado, "C4" = Clear Creek County, "H2" = metallic minerals, probably made in the 1800's, author's last name begins with an "I".

G6714.M63 1943 .U5

"G6714" = a city in Italy, "M63" = Milan, made in 1943, author's name begins with a "U".

G4314.D4C1 1957 .U6

"G4314" = a city in Colorado, "D4" = Denver, "C1" = physical sciences, made in 1957, author's name begins with a "U".