ASM Site Numbering and Quadrangle System
The system used by the Arizona State Museum for designating sites is based on one devised originally by Gila
Pueblo in the late 1920s. Modifications have been made to eliminate inconsistencies in the older system. Both
systems are based on the premise that a relatively large area can be systematically subdivided and that a site can be
located with respect to these smaller units of area by means of a simple designation. In the Arizona State Museum
system a five-part site designation is used; for example, AZ U:15:2(ASM).
The Five Parts of a Site Designation
- A standard political division such as a state, territory, or small country, is considered as the basic unit of
area for the survey. The name of this standard political division becomes the first component of the site
designation (see Figure 1). Although such a name may be abbreviated for convenience (as in the example above),
it can never be omitted. The name or abbreviation of the standard political division must always appear as
the first component of the site designation.
- The standard political division is divided into quadrangles based on the standard meridians and parallels.
Each quadrangle measures one degree of longitude and one degree of latitude. Quadrangles are designated
by the letters of the alphabet, beginning in the northwest corner and ending in the southeast corner of the
If there are more than 26 quadrangles in the political division, the additional ones are identified by double
letters (AZ AA). In Arizona the first complete quadrangle is AZ A, in the northwest corner of the state,
while the last quadrangle is AZ FF in the southeast corner. Our example, AZ U:15:2(ASM), is a site in a
quadrangle in the south-central part-of the state. The letter(s) identifying the quadrangles are always the
second component of the site designation.
- The third component of the site designation is the number of a subdivision of the quadrangle, which is
called a rectangle. In every quadrangle there are 16 rectangles, and each rectangle represents one U.S.G.S.
15’ map. Within a quadrangle the rectangles are numbered 1 to 16, beginning in the northwest corner and
ending in the southeast corner of the quadrangle (See AZ S in Figure 1). The relative position of a given
rectangle is always the same within any quadrangle. For example, rectangle 4 is invariably in the northeast
corner. In our example, the Site AZ U:15:2(ASM) is in rectangle 15 of quadrangle U in Arizona. The
number of the rectangle is always the third component of the site designation.
- A number identifying the site within the rectangle constitutes the fourth component of the site designation.
The sites in a rectangle are numbered serially as they are found and recorded. The site AZ U:15:2(ASM)
was the second one recorded in rectangle 15 of quadrangle U in Arizona. Since the site numbers within a
rectangle are assigned serially, they carry no implication about relative geographical position.
- The final component of the site number is the suffix (ASM), which is essential to indicate that the number
was assigned by ASM. Several other institutions (ASU, BLM, MNA, some branches of the NPS) have
adopted a similar site number format, but on their own numbering systems. Therefore, while AZ
U:15:2(ASM) and AZ U:15:2(ASU) are both in the AZ U:15 rectangle, they are not the same site.
How to Request a Site Number
Arizona State Museum Site Files Maps
ASM records the site numbers by U.S.G.S 15’ maps, but the sites are plotted on paper copies of U.S.G.S. 7.5’ maps
(1:24,000). These maps are filed in bound books by the quadrangle (e.g., AZ U:15) and, within the quadrangle in
the order NW, NE, SW, SE. Therefore, the next site number for a site in the Magma quad will be given a number in
AZ U:15, and will be plotted on AZ U:15:NW, which is the quadrangle designation for the U.S.G.S. Magma quad.
8/2/00 Adapted from “The Archaeological Survey of the Arizona State Museum,” by William W. Wasley, 1980, Arizona State
Museum Archaeological Series 128:9-12.
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