A quadripoint is a point on Earth where four distinct political territories meet. The territories can be of different types, such as national and provincial. In North America, several such places are commonly known as Four Corners. Several examples exist throughout the world that use other names.
Usage The word quadripoint does not appear in the Oxford English Dictionary or Merriam-Webster Online, though it has been used since 1964 by the Office of the Geographer of the United States Department of State, and appears in the Encyclopædia Britannica, as well as in the World Factbook articles on Botswana, Namibia, Zambia, and Zimbabwe, dating as far back as 1990.
History
An early instance of four political divisions meeting at a point is the Four Shire Stone in Moreton-in-Marsh, England (attested in the Domesday Book, 1086, and mentioned since 969 if not 772); until 1931, it was the meeting point of the English counties of Gloucestershire, Oxfordshire, Warwickshire, and Worcestershire.
Between 1839 and 1920, there was a quadripoint at the convergence of Belgium, Prussia/Germany, the Netherlands, and Moresnet at Vaalserberg. Moresnet was never truly a country but rather only a neutral territory or condominium of the Netherlands and Prussia (originally), and of Belgium and Germany (ultimately). Subsequent political changes have restored its quadripartition along municipal lines (Kelmis, Plombieres within Belgium) since 1976 (though it has also enjoyed fivefold partition along municipal lines at times).
Four-nation quadripoints
Botswana–Namibia–Zambia–Zimbabwe
Some older sources claimed that a quadripoint existed in Africa,"Guinness Book of Records", 1979 et seq.; see "Shortest Frontier" where the borders of Namibia, Botswana, Zambia, and Zimbabwe come together at the confluence of the Cuando (also called Chobe) and Zambezi rivers. In the absence of legal clarity, it is now widely believed that instead, two separate tripoints exist about apart (but see below regarding due diligence preceding bridge construction).
The causes of this unusual border configuration lie in the Scramble for Africa. By the 1880s, the British Empire and the British South Africa Company occupied much of Southern Africa, including the Cape Colony, Rhodesia and Bechuanaland. The German Empire also began occupying African territories in the 1880s, namely German South West Africa and German East Africa. Seeking a more efficient route between these two colonies via the Zambezi River, Germany signed the Heligoland–Zanzibar Treaty with Britain in 1890, thereby gaining control of a narrow salient called the Caprivi Strip. Following the South West Africa campaign in World War I, the Union of South Africa captured and administered South West Africa, including the Caprivi Strip. In the 1960s, with the decolonisation of Africa, the remaining British colonies in Southern Africa declared their independence, including Zambia in 1964, Rhodesia (now Zimbabwe) in 1965, and Botswana in 1966. By the time of Rhodesia's declaration of independence in 1965, there were four independent sovereign states whose territorial boundaries came very close to a quadripoint: the Republic of South Africa (occupying the Caprivi Strip) to the west, the newly independent Republic of Zambia to the north; the newly independent Rhodesia to the east; and the British Bechuanaland Protectorate to the south.
In 1970, South Africa (which at the time occupied Namibia) informed Botswana that there was no common border between Botswana and Zambia, claiming that a quadripoint existed. As a result, South Africa claimed that the Kazungula Ferry, which links Botswana and Zambia at the quadripoint, was illegal. Botswana firmly rejected both claims. There was a confrontation and shots were fired at the ferry; some years later, the Rhodesian Army attacked and sank the ferry, maintaining that it was serving military purposes. Ian Brownlie, who studied the case, wrote in 1979 that the possibility of a quadripoint could not be definitively ruled out at that time.
In August 2007, the governments of Zambia and Botswana announced a deal to construct a bridge at the site to replace the ferry."Zambia and Botswana reach Kazungula bridge deal." Palapye News blog. Retrieved 12 November 2007. The existence of a short boundary of about between Zambia and Botswana was agreed by all four states in the 2006–10 period, and is shown in the African Development Fund project map. This matches the data kept by the Office of the Geographer under the U.S. Department of State. However, the Anglo-German agreement of 1890 stipulates that the thalweg junction of the Chobe and Zambezi, which today falls within the demarcated limits of Zimbabwe, is the eastward limit of the Caprivi Strip (in today's Namibia). Moreover, it was reported in 2014 that Namibia actually granted Botswana and Zambia an easement to build their bridge across what all three parties concurred was Namibian territory. The Kazungula Bridge opened for traffic in May 2021.
Cameroon–Chad–Nigeria–United Kingdom A true four-country point did formerly exist in Africa for a period of eight months during 1960 and 1961, in southern Lake Chad, at the location of the present Cameroon–Chad–Nigeria tripoint. Upon the 1 October 1960 independence of Nigeria, that borderpoint became common to the latter three countries and the territory of Northern Cameroons, which was still governed under United Nations mandate by the United Kingdom, until it was finally integrated into Nigeria on 1 June 1961. This is the only known quadricountry borderpoint not involving condominial territories.
Quadripoints within and between nations
Quadripoints can exist at the meeting of political subdivisions of any type or level. The most common are in the United States and Canada, where the grid-based Public Land Survey System (PLSS) and Dominion Land Surveys (DLS), respectively, resulted in a large number of quadripoints at the corners of survey units such as DLS townships, PLSS townships, sections, and various other gridded subdivisions. The borders of U.S. counties and towns are often defined by survey townships. There are dozens of quadripoints between U.S. counties, hundreds between U.S. municipalities, and indeed thousands (of usually bilateral ones) on the edges of checkerboard-patterned Indian reservations and other federally reserved territories. But of all the quadripoints that exist, the most noted are a few dozen that are situated on international borders, and about a dozen others involve primary national subdivisions (such as provinces or states).
Among the international quadripoints (examples below), a few general types can be distinguished. In the absence of four-country points, three-country quadripoints are perhaps most significant. These combine two divisions of one country with (one each of) two other countries. But there also exist merely binational quadripoints—of several varieties. Some of these combine two subdivisions of two countries, others three subdivisions of one country with (one of) another; while still others occur at points where international boundaries appear to touch or cross themselves—with or without subdivision—or where an international boundary appears to bifurcate around disputed territories.
Also below, by country, are some subnational quadripoints composed of subdivisions.
Algeria–Mali–Mauritania Two districts of Adrar Province, Algeria—namely Bordj Badji Mokhtar and Reggane—meet the Tombouctou Cercle of Tombouctou Region, Mali, and the Bir Mogrein Department of Tiris Zemmour Region, Mauritania.
Argentina The Argentine provinces of La Pampa, Río Negro, Mendoza, and Neuquén may meet at . Río Negro has disputed this since a 1966 resurvey cast the exact boundary convergence into some doubt.
Austria–Germany The summit of Sorgschrofen forms a quadripoint between two German and two Austrian municipalities, Pfronten and Bad Hindelang in Bavaria, Germany, and Schattwald and Jungholz in Tyrol, Austria, the Austrian municipality of Jungholz being connected to the rest of the territory of Austria just by the single point, according to the 1844 border treaty between the Kingdom of Bavaria and the Austrian Empire.
Bangladesh–India The Bangladesh-India border formerly included nearly 200 enclaves. Almost all of these were extinguished by the Land Boundary Agreement between the two states, effective after 31 July 2015, which exchanged all first-order enclaves. The international boundary touched itself at one or possibly two locations shared by India (West Bengal state, Cooch Behar district) and Bangladesh (Rangpur Division, Lalmonirhat District). A confirmed instance occurred in Mathabhanga subdivision and a less definite one in Mekhliganj subdivision (of Cooch Behar), involving the Bara Saradubi enclave of Hatibandha thana and the Jote Nijjama enclave of Patgram thana (of Lalmonirhat), respectively; both were eliminated by the agreement. The international stature of these enclaves had been intermittent since Mughal times and was a result of the Radcliffe Award of 1947.
Belgium–Netherlands
The international boundary touches (or crosses) itself, without imparting political subdivision, within the commingled municipalities of Baarle-Nassau (North Brabant, Netherlands) and Baarle-Hertog (Antwerp, Belgium). The peculiar situation, which occurs at Baarle but once (at the touchpoint of Belgian enclaves H1 and H2), has existed at least cadastrally since about 1198, but its current international distinction dates only from 1830.
Benin–Burkina Faso Since 2009, Benin and Burkina Faso have jointly administered a neutral zone (at ) called Kourou or Koalou that lies tangent to their boundary junction with Togo, producing the sort of tricountry quadripoint that adjoined the defunct Moresnet neutral zone illustrated above.
Canada
The creation of the Canadian territory of Nunavut resulted in the creation of a quadripoint between the provinces of Saskatchewan and Manitoba and the territories of Nunavut and Northwest Territories (NWT). Nunavut was officially separated from the Northwest Territories in 1999, though the boundaries had been defined in 1993 by the Nunavut Act and the Nunavut Land Claims Agreement. Both documents define Nunavut's boundary as including the "intersection of 60°00'N latitude with 102°00'W longitude, being the intersection of the Manitoba, Northwest Territories and Saskatchewan borders". However, the northernmost point of the Manitoba–Saskatchewan border as surveyed is slightly off from 60° north 102° west; therefore, the laws were not perfectly clear about whether the Nunavut–NWT boundary was to meet the others in a quadripoint or not. In 2014, the Survey General Branch (SGB) of Natural Resources Canada established the monument at the northern terminus of the Manitoba-Saskatchewan boundary as the southern terminus of the NWT-Nunavut boundary, confirming the creation of a quadripoint between the two provinces and two territories.
Canada–United States Both of the only known international quadripoints in the Americas occur on the Canada–United States border along remote mountain crests. One, which joins the Canadian provinces of Alberta (Improvement District No. 4) and British Columbia (Regional District of East Kootenay) with the Montana counties of Flathead and Glacier where the 49th parallel crosses the Continental Divide also unites an international peace park comprising national parks of both countries (Waterton Lakes in Canada and Glacier in the United States). It has been a politically important and precisely stipulated international boundary point since 1818; has been monumented since 1876 (now by a hollow metallic obeliskoid marker numbered 272); and has maintained a quadripartite status since 1893.Boundaries of the United States and the Several States, Van Zandt, supra, p. 14, 21