A survey township, sometimes called a Congressional township or just township, as used by the United States Public Land Survey System, is a nominally-square area of land that is nominally six U.S. survey miles (about 9.66 km) on a side. Each 36-square-mile (about 93.2 km2) township is divided into 36 sections of one square mile (640 acres, roughly 2.6 km2) each.  The sections can be further subdivided for sale.
The townships are referenced by a numbering system that locates the township in relation to a principal meridian (north-south) and a base line (east-west). For example, Township 2 North, Range 4 East is the 4th township east of the principal meridian and the 2nd township north of the base line. Township (exterior) lines were originally surveyed and platted by the US General Land Office using contracted private survey crews. Later survey crews subdivided the townships into section (interior) lines. Virtually all lands covered by this system were sold according to those boundaries and are marked on the U.S. Geological Survey topographic maps.
Prior to standardization, some of the Ohio Lands (the United States Military District, the Firelands and the Connecticut Western Reserve) were surveyed into townships of 5 miles (8.0 km) on each side. These are often known as Congressional Townships.  
Sections are divided into quarter-sections of 160 acres (65 ha) each and quarter-quarter sections of 40 acres (16 ha) each. In the Homestead Act of 1862, one quarter-section of land was the amount allocated to each settler. Stemming from that are the idiomatic expressions, "the lower 40", the 40 acres on a settler's land that is lowest in elevation, in the direction towards which water drains toward a stream, and the "back forty", the portion farthest from the settler's dwelling.
Survey townships are distinct from civil townships. A survey township is used to establish boundaries for land ownership, while a civil township is a form of local government. In states with civil townships, the two types of townships often coincide. County lines, especially in western states, usually follow survey township lines, leading to the large number of rectangular counties in the Midwest, which are agglomerations of survey townships. 
In western Canada, the Dominion Land Survey adopted a similar format for survey townships, which do not form administrative units. These townships also have the area of 36 square miles (six miles by six miles).
The Public Land Survey System (PLSS) is the surveying method developed and used in the United States to plat, or divide, real property for sale and settling. Also known as the Rectangular Survey System, it was created by the Land Ordinance of 1785 to survey land ceded to the United States by the Treaty of Paris in 1783, following the end of the American Revolution. Beginning with the Seven Ranges in present-day Ohio, the PLSS has been used as the primary survey method in the United States. Following the passage of the Northwest Ordinance in 1787, the Surveyor General of the Northwest Territory platted lands in the Northwest Territory. The Surveyor General was later merged with the General Land Office, which later became a part of the U.S. Bureau of Land Management (BLM). Today, the BLM controls the survey, sale, and settling of lands acquired by the United States.
The Dominion Land Survey is the method used to divide most of Western Canada into one-square-mile (2.6 km2) sections for agricultural and other purposes. It is based on the layout of the Public Land Survey System used in the United States, but has several differences. The DLS is the dominant survey method in the Prairie provinces, and it is also used in British Columbia along the Railway Belt, and in the Peace River Block in the northeast of the province.
A township in some states of the United States is a small geographic area.
The Land Ordinance of 1785 was adopted by the United States Congress of the Confederation on May 20, 1785. It set up a standardized system whereby settlers could purchase title to farmland in the undeveloped west. Congress at the time did not have the power to raise revenue by direct taxation, so land sales provided an important revenue stream. The Ordinance set up a survey system that eventually covered over three-quarters of the area of the continental United States.
The chain is a unit of length equal to 66 feet. It is subdivided into 100 links or 4 rods. There are 10 chains in a furlong, and 80 chains in one statute mile. In metric terms, it is 20.1168 m long. By extension, chainage is the distance along a curved or straight survey line from a fixed commencing point, as given by an odometer.
The Willamette Stone was a small stone obelisk originally installed by the Department of Interior in 1885 in the western hills of Portland, Oregon in the United States to mark the intersection and origin of the Willamette meridian and Willamette baseline. It replaced a cedar stake placed by the Surveyor General of the Oregon Territory in 1851; this stake defined the grid system of sections and townships from which all real property in the states of Oregon and Washington has been measured following the Donation Land Claim Act of 1850. The Willamette meridian runs north–south, and the Willamette baseline runs east–west through the marker. The easternmost northeast corner of Washington County is sited on the marker.
In U.S. land surveying under the Public Land Survey System (PLSS), a section is an area nominally one square mile, containing 640 acres, with 36 sections making up one survey township on a rectangular grid.
The Michigan meridian is the principal meridian used as a reference in the Michigan Survey, the survey of the U.S. state of Michigan in the early 19th century. It is located at 84 degrees, 21 minutes and 53 seconds west longitude at its northern terminus at Sault Ste. Marie, and varies very little from that line down the length of the state.
Strongfield is a village in the Canadian province of Saskatchewan within the Rural Municipality of Loreburn No. 254 and Census Division No. 11. It lies approximately 100 km south of the City of Saskatoon on Highway 19 between its sister communities of Hawarden and Loreburn.
The Alberta Township System (ATS) is a land surveying system used in the Canadian province of Alberta and other parts of western Canada.
Ayers Township is one of thirty townships in Champaign County, Illinois, USA. As of the 2010 census, its population was 453 and it contained 195 housing units.
Brown Township is a township in Champaign County, Illinois, USA. As of the 2010 census, its population was 1,995 and it contained 816 housing units.
East Bend Township is a township in Champaign County, Illinois, USA. As of the 2010 census, its population was 584 and it contained 257 housing units. East Bend Township was named for a meander of the Sangamon River.
Newcomb Township is a township in Champaign County, Illinois, USA. As of the 2010 census, its population was 1,292 and it contained 492 housing units.
The Tallahassee meridian, in longitude 84° 16′ 37.59″ west from the prime meridian at Greenwich, runs north and south from the initial point on the base line at Tallahassee, in latitude 30° 26′ 04.12″ north, and as a principal meridian governs the surveys in Florida and Alabama as part of the Public Land Survey System.
The Congress Lands West of Miami River was a land tract in southwest Ohio that was established by the Congress late in the 18th century. It is located south of the Greenville Treaty Line, east of Indiana, and north of the Great Miami River. The original survey in 1798 contained a triangular shaped slice of land, now located in Indiana, that extended to the Greenville line as it ran from Fort Recovery to opposite the mouth of the Kentucky River.
The Twelve Mile Square Reservation, also called the Twelve Mile Square Reserve, was a tract of land in Ohio ceded by Indians to the United States of America in the Treaty of Greenville in 1795. This particular area of land immediately surrounding Fort Miami was considered to be of strategic importance by the United States government representatives. It was subsequently surveyed in a manner different from surrounding land, and lots sold, or granted, to settlers.
The Two Mile Square Reservation or Two Mile Square Reserve was a tract of land in Ohio ceded by Native Americans to the United States of America in the Treaty of Greenville in 1795. It was subsequently surveyed in a manner different from surrounding land, and lots sold to settlers.
North and East of the First Principal Meridian is a survey and land description in the northwest part of the U.S. state of Ohio.
Sargent Township is a civil township in Sargent County, North Dakota, United States.