The original intent was to establish townships exactly 6 miles square with subdivisions of 36 one mile square sections. But because of technical problems including crude measuring instruments and earth curvature issues, the present system is now a culmination of revisions addressing these problems. This "new" system also replaced "metes and bounds" surveys of the U.S. colonial period.
As it still is today, the original system's initial points started off a true north-south line know as a principal meridian and a true east-west base line corresponding to a parallel of latitude (see sample grid). These two lines constituting the main axes of the survey system, are divided into tracts approximately 24 miles squares north snd south of the base line, subdivided into 16 townships each of which are then subdivided into 36 sections. This theoretical section, township and range grid (or STR) converges as it moves north so the actual survey grid (and the acreage) changes in tracts and from tract to tract when corners are closed and when compromised by inaccurate surveys.
Understanding and Reading Township and Range MapsDownload this township/range image for illustration: A Basic Township and Range Grid
A township measures the north/south distance from its parallel base line. A township that theoretically measures 6 miles and is that first six miles north of the base line is described as township one north and written as T1N. The second six miles would be T2N, then T3N and so on.
A township that surveys the the first six miles south and below the base line is described as township one south and written as T1S. The second six miles would be T2S, T3S and so on.
A range measures the east/west distance from its dedicated principal meridian. Like townships, ranges are also 6 miles in distance so the first six miles west of the principal meridian would be described as range one west and written as R1W, the second would be R2W. The first six miles east would be R1E then R2E and so on.
With two grid coordinates off the 24 mile mosaic (example: T1N,R1N), you can determine the exact square township and the process of land or forest location begins.
Determining Sections and Quarter SectionsFirst, download this section image for illustration: A Basic Section Grid
Townships are divided into 36 miles square "sections" and each section is identified with a number based on its grid position. The northeastern-most section is considered the first section, labeled "1", with those following taking the next number to the west to complete a six section first row. Below section 6 is the second row's section 7 and each is numbered to 12 going east. This snakelike pattern is continued to the southeastern-most section 36 and all these sections make up the township.Now, download this quarter section image for illustration: A Basic Quarter Section Grid
Sections (each being 660 acres) are again subdivided into quarters. They are usually described as the northeast, northwest, southeast, and southwest quarters of the section. These "quarter sections" contain 160 acres.Not done yet. Each of the above quarters can be divided again into quarters and these divisions called a "forty" or 40 acres. So, when describing the survey description's STR, the smallest quarter is followed by the largest quarter, then the section, and then the township and range. One example could be: SE 1/4, NE 1/4, S14, T8S, R2E and is read as the southeast quarter of the northeast quarter of section fourteen, township eight south, range two east.