The Meades Ranch Triangulation Station is a survey marker in Osborne County in the state of

Kansas Kansas ( ) is a landlocked U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to the west. Kansas is named a ...

in the

Midwestern United States The Midwestern United States (also referred to as the Midwest, the Heartland or the American Midwest) is one of the four census regions defined by the United States Census Bureau. It occupies the northern central part of the United States. It ...

. The marker was initially placed in 1891. From 1901, it was the reference location for establishing a system of horizontal measurement in the United States, known as

geodetic datum A geodetic datum or geodetic system (also: geodetic reference datum, geodetic reference system, or geodetic reference frame, or terrestrial reference frame) is a global datum reference or reference frame for unambiguously representing the positi ...

. In 1913, the datum was adopted across all of

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

, and the system revised and formalized as the North American Datum of 1927 (NAD27). A similar reference for vertical measurement was established in 1929 as the

National Geodetic Vertical Datum of 1929 The National Geodetic Vertical Datum of 1929 is the official name since 1973 of the vertical datum established for vertical control surveying in the United States of America by the General Adjustment of 1929. Originally known as Sea Level Datum ...

. The NAD27 was later supplanted by the North American Datum of 1983 (NAD83), which was formally adopted by the United States in 1989 and Canada in 1990; the new system moved the reference point to a point in the

Earth's core The internal structure of Earth are the layers of the Earth, excluding its atmosphere and hydrosphere. The structure consists of an outer silicate solid crust, a highly viscous asthenosphere, and solid mantle, a liquid outer core whose flow g ...

, and the Meades Ranch marker lost its special significance to the geodetic datum system. In 1973, the site was listed in the

National Register of Historic Places The National Register of Historic Places (NRHP) is the Federal government of the United States, United States federal government's official United States National Register of Historic Places listings, list of sites, buildings, structures, Hist ...

as the Geodetic Center of the United States.

History

In surveying, a

is a point or set of points used to establish a coordinate system. By designating the location of one point, and the direction from that point to a second point, one can establish a system relative to which other points can be located and mapped. As one surveys a larger area over which the curvature of the Earth becomes significant, it also becomes necessary to define an

ellipsoid An ellipsoid is a surface that can be obtained from a sphere by deforming it by means of directional Scaling (geometry), scalings, or more generally, of an affine transformation. An ellipsoid is a quadric surface; that is, a Surface (mathemat ...

: a curved surface that approximates the shape of the Earth in the area of interest. The first nationwide datum in the United States was established in 1879. At that time, a region of contiguous triangulation existed from Maine to Georgia. The New England Datum was chosen with a benchmark in Maryland, near the middle of this region, as the horizontal datum, and a second Maryland mark used to define the

azimuth An azimuth (; from ) is the horizontal angle from a cardinal direction, most commonly north, in a local or observer-centric spherical coordinate system. Mathematically, the relative position vector from an observer ( origin) to a point ...

(horizontal) direction. To account for the Earth's curvature, the datum used a model called the

Clarke Clarke is a surname which means "clerk". The surname is of English and Irish origin and comes from the Latin . Variants include Clerk and Clark. Clarke is also uncommonly chosen as a given name. Irish surname origin Clarke is a common surname ...

spheroid, developed in 1866.

Meades Ranch station

The

United States Coast and Geodetic Survey The United States Coast and Geodetic Survey ( USC&GS; known as the Survey of the Coast from 1807 to 1836, and as the United States Coast Survey from 1836 until 1878) was the first scientific agency of the Federal government of the United State ...

established a

triangulation station A triangulation station, also known as a trigonometrical point, and sometimes informally as a trig, is a fixed surveying station, used in geodetic surveying and other surveying projects in its vicinity. The station is usually set up by a map ...

, officially known as the Meades Ranch Triangulation Station, in 1891. The location lay near the intersection of two transcontinental arcs of triangulation: one running from the Atlantic to the Pacific Ocean, roughly following the 39th parallel; the other running from Mexico to Canada, along the 98th meridian. In 1901, the Meades Ranch station was chosen as the United States standard horizontal

datum Data ( , ) are a collection of discrete or continuous value (semiotics), values that convey information, describing the quantity, qualitative property, quality, fact, statistics, other basic units of meaning, or simply sequences of symbols t ...

: the point relative to which all land measurements in the nation were made. The choice was based on the station's location near the geographic center of the U.S. and near the intersection of the two arcs of triangulation, and because it minimized the number of changes in previously published positions. Its position was officially set as 39°13'26.686" N and 98°32'30.506" W; the

direction to a triangulation station near

Waldo Waldo may refer to: People and fictional characters * Waldo (given name), a list of people and fictional characters with the name * Waldo (surname), a list of people * Waldo (footballer), Brazilian footballer Waldo Machado da Silva (1934–20 ...

, southwest of Meades Ranch, was officially set as 75°28'14.52" west of south. In 1913, the chief astronomer of the Dominion of Canada Astronomical Observatory and the director of the Comisión Geodésica Mexicana announced that their organizations would use the Meades Ranch location as their standard datum. In light of this, its name was changed to the "North American Datum". Horizontal Control Network of the United States June 1931

Horizontal Control Network of the United States June 1931

As more new surveys and previously isolated survey networks were incorporated into the system, it became increasingly difficult to make the necessary corrections. By the mid-1920s, it was realized that the coordinate system needed to be adjusted. From 1927 to 1932, the approximately 25,000 existing control locations were recalculated and a new coordinate system developed, known as NAD27. The new system continued to use the 1901 coordinates of Meades Ranch as its horizontal datum, and the Clarke spheroid as its model for the Earth's surface. However, it now defined horizontal directions in terms of 175 Laplace azimuths, which use astronomical azimuths corrected for the difference between the astronomic and geodetic meridians. Under NAD27, the azimuth to the Waldo station changed by about 5". In 1973, the Meades Ranch site was added to the

, under the name "Geodetic Center of the United States".

NAD83

Following the establishment of NAD27, it was noted that it produced a discrepancy of about in latitudes in the northern part of the northern U.S. state of

Michigan Michigan ( ) is a peninsular U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest, Upper Midwestern United States. It shares water and land boundaries with Minnesota to the northwest, Wisconsin to the west, ...

, necessitating a regional adjustment for the states of Michigan and

Wisconsin Wisconsin ( ) is a U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest of the United States. It borders Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake Michigan to the east, Michig ...

. As the survey network was extended further north into Canada, similar discrepancies appeared. The problem proved to be systemic: It had been assumed that the differences between the Clarke spheroid and the actual geoid were negligible, whereas these differences actually introduced significant errors. The relatively small number and large separation of the points used to develop NAD27, the limited computational power available to its designers, and the movement of

tectonic plates Plate tectonics (, ) is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of , an idea developed durin ...

also led to inconsistencies in NAD27 coordinates. Datum Shift Between NAD27 and NAD83

To address these, a new datum was developed, designated NAD83. It replaced the Clarke spheroid with a new ellipsoid, the Geographic Reference System 1980, centered at the Earth's

center of mass In physics, the center of mass of a distribution of mass in space (sometimes referred to as the barycenter or balance point) is the unique point at any given time where the weight function, weighted relative position (vector), position of the d ...

as determined by the

Bureau International de l'Heure The International Time Bureau (, abbreviated BIH), seated at the Paris Observatory, was the international bureau responsible for combining different measurements of Universal Time. The bureau also played an important role in the research of time ...

. The new datum was based on adjustment of 250,000 points, including 600 satellite Doppler stations. NAD83 was officially adopted by the U.S. government in 1989, and by the Canadian government in 1990. Under the new system, Meades Ranch lost its special standing, and became one of thousands of stations.

Description

North America geodetic center - replica plaque 1

As of 2012, the location of the Meades Ranch station was (in NAD83(2011);

WGS 84 The World Geodetic System (WGS) is a standard used in cartography, geodesy, and satellite navigation including GPS. The current version, WGS 84, defines an Earth-centered, Earth-fixed coordinate system and a geodetic datum, and also descri ...

location may be very slightly off). It lies about north of

Lucas Lucas or LUCAS may refer to: People * Lucas (surname) * Lucas (given name) Arts and entertainment * Luca Family Singers, or the Lucas, a 19th-century African-American singing group * Lucas, a 1960s Swedish pop group formed by Janne Lucas Perss ...

and about southwest of

Tipton Tipton is an industrial town in the metropolitan borough of Sandwell, in the county of the West Midlands (county), West Midlands, England. It had a population of 38,777 at the 2011 UK Census. It is located northwest of Birmingham and southeas ...

. The station is on a low grassy ridge in a pasture. It is marked by a bronze disc, inscribed "Meades Ranch 1891", embedded in the top of a dome-shaped concrete marker in diameter, rising about above ground level. Two reference marks and an azimuth mark are located nearby. The Meades Ranch station is on private land, with no public access. A replica of the station marker, with a Kansas historical marker explaining its significance, is located at , in a roadside rest area beside U.S. Highway 281 at the northern edge of

Osborne, Kansas Osborne is a city in and the county seat of Osborne County, Kansas, Osborne County, Kansas, United States. As of the 2020 United States census, 2020 census, the population of the city was 1,335. History Settlers from southeastern Pennsylvania ...

, northwest of the Meades Ranch site.

References

External links

1940 re-installation

two journal essays {{National Register of Historic Places Monuments and memorials on the National Register of Historic Places in Kansas

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...