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In U.S. land surveying, a section is an area nominally one mile square, containing 640 acres (2.6 km²). Nominally, 36 sections make up a survey township. Some sections vary slightly in size to compensate for the fact that the Earth is round. These unusually sized sections are generally placed at the westernmost or easternmost edges of townships.
The legal description of a tract of land in the parts of the United States that use this system includes the name of the state, name of the county, township number, range number, section number, and portion of a section. Sections are customarily surveyed in halves and quarters, and further subdivision in halves and quarters is common. A quarter quarter section is 40 acres (160,000 m²), and is the smallest unit of agricultural land commonly surveyed. The phrases "front 40" and "back 40," referring to fields of crops on a farm, refer to quarter quarter sections.
History
The existence of section lines made property descriptions far more straightfoward than the old "metes and bounds" system. The establishment of standard east-west and north-south lines ("township" and "range lines") meant that deeds could be written without regard to temporary terrain features such as trees, piles of rocks, fences, and the like, and be worded in the style such as "Lying and being in Township 4 North; Range 7 West; and being the northwest quadrant of the southwest quadrant of said section," an exact description in this case of 40 acres, as there are 640 acres in a square mile. (The existence of such documents is a major reason why the U.S. will never be able to adopt the metric system in its entirety.)
United States
The importance of "sections" was greatly enhanced by the passage of the Northwest Ordinance of 1787 by the U.S. Congress. This law provided that lands outside the then-existing states could not be sold, otherwise distributed, or opened for settlement prior to being surveyed. (Many of the Founders were land surveyors and speculators, including especially George Washington.) The standard way of doing this was to divide the land into sections. An area six sections by six sections would define a township. Within this area, one section was designated as school land. As the entire parcel would not be necessary for the school and its grounds, the balance of it was to be sold with the monies to go into the construction and upkeep of the school.
In many jurisdictions, roads were run along every section line, giving access to previously remote areas and serving in many instances as firebreaks. In some locales, these lines were designated as the basis for a street numbering system; in Tulsa, Oklahoma, for example it can be correctly assumed that 190th Street is exactly seventeen miles beyond 20th Street, each "block" representing one-tenth of a mile.
Canada
Numbering within a township
Every township is divided into 36 sections, each usually one-mile square. Sections are numbered within townships as follows (north at top):
United States Canada
6 5 4 3 2 1 31 32 33 34 35 36
7 8 9 10 11 12 30 29 28 27 26 25
18 17 16 15 14 13 19 20 21 22 23 24
19 20 21 22 23 24 18 17 16 15 14 13
30 29 28 27 26 25 7 8 9 10 11 12
31 32 33 34 35 36 6 5 4 3 2 1
See also
The Canadian Dominion Land Survey also uses a section of one square mile.
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