Earth Science Laboratory
Follow the color coding of the coordinates below and match them with the diagram at the left (Note: this only works if you are viewing this document on-line or if you have a color hard copy).  Using the township and range coordinates system, the points on the grid are located as follows:

Point A is located at "SW 1/4 of NE 1/4 of Section 1, T20S, R7E"

Point B is located at "NW 1/4 of SW 1/4 of Section 21, T20S, R7E"

Point C is located at "SW 1/4 of SE 1/4 of Section 34, T20S, R7E"


    The township and range grid system is based upon subdivisions of a single township, which is a square parcel of land that is 36 square miles in area (6 miles North-South X 6 miles East-West). The boundary lines that run east-to-west, dividing North from South are called township lines. The boundary lines running north to side and divide East from West are called range lines. The township and range coordinates of adjacent townships depend upon the context of the existing township and range lines. In the above example, the detailed township is located within T20S, which begins at Section 1 and ends at Section 36. The township to the south is T21S, while the township to the north is T19S because it is closer to the T-Zero line. Similarly, the township is located within the range R7E; walking further east causes the range numbers to go up, while walking west causes them to decrease.

Subdividing a section: A township is divided up into 36 sections, each of which is 1 square mile (1 mile X 1 mile). Note that Section 1 is always located in the northeast corner of a township, that Section 36 is always located in the southeast corner, and that the section numbers zig-zag, East to West, within a township. Although only one township is shown above, there are 8 other townships located on all sides of the perimeter boundary. Therefore, the section numbering system of every other township repeats itself in similar fashion. You must subdivide a section twice; first, divide the section into quarter sections, then select one of the quarter sections and subdivide it one more time. The correct sequence of location data begins with the smallest location.

Draw a one-mile section measuring template on tracing paper: To subdivide a section on a topographic map, use a sheet of tracing paper and a pencil. First, take the corner of the tracing paper and mark off 1 mile along one edge along the graphic scale located at the southern part of your map. Then, measure 1 mile along the other edge of the tracing paper. Use a straight edge to draw a box from the 1 mile markings, subdivide it into quarter sections, and subdivide the quarter sections.  A similar section measuring template may also be made from an overhead transparency rather than tracing paper.

Copyright ©1996 by William K. Tong