{{Use Australian English|date=June 2020}} {{Use dmy dates|date=July 2022}} Today the Northern Territory's land borders are defined to the west by the 129° east longitude (<abbr title="129th meridian east longitude">129° east</abbr>) with Western Australia, to the south by the 26th parallel south latitude (<abbr title="26th parallel south latitude">26° south</abbr>) with South Australia and to the east by 138° east longitude (<abbr title="138th meridian east longitude">138° east</abbr>) with Queensland; however, this is not where all borders are actually marked on the ground.
The Northern Territory boundaries are shared with the West Australian border, the South Australian border, and the Queensland border.
==History== right|thumb|250px|Map showing the creation of the colonies/states and mainland territories.
===1788–1832=== In 1788, Governor Phillip claimed the continent of Australia as far west as the 135th meridian east longitude (<abbr title="135th meridian east longitude">135° east</abbr>) in accordance with his commission.<ref name="NAA1787">{{cite web | url = http://www.foundingdocs.gov.au/item.asp?dID=35 | title = Governor Phillip's Instructions 25 April 1787 (UK) | work = Documenting a Democracy | publisher = National Archives of Australia | access-date = 2006-05-28 | url-status = dead | archive-url = https://web.archive.org/web/20060615195616/http://foundingdocs.gov.au/item.asp?dID=35 | archive-date = 15 June 2006 }}</ref> (26 January 1788 – Map)
On 16 July 1825, the western boundary of New South Wales was relocated to the line of <abbr title="129th meridian east longitude">129° east</abbr> to take in the new settlement at Melville Island.<ref name="TaylorP118">{{cite book | last = Taylor | first = Peter | year = 1990 | title = The Atlas of Australian History | publisher = Child & Associates Publishing Pty Ltd | location = Sydney, New South Wales, Australia | isbn = 0-86777-429-0 | pages = 118–9 | chapter = Chapter 10: Government and the States}}</ref> (16 July 1825 – Map). From 1825 to 1829 129° east was the NSW border.
Following the settlement of the Swan River Colony in 1829 (2 May 1829 – Map), its eastern boundary was declared to be 129° east, coinciding with the western boundary of New South Wales at the time.<ref name="NAA1831transcript">{{cite web | url = http://www.foundingdocs.gov.au/resources/transcripts/wa5i_doc_1831.pdf | title = Transcript of Commission appointing Stirling Governor and Commander-in-Chief 4 March 1831 (UK) | work = Documenting a Democracy | publisher = National Archives of Australia | access-date = 2006-05-28 | archive-url = https://web.archive.org/web/20120206211244/http://foundingdocs.gov.au/resources/transcripts/wa5i_doc_1831.pdf | archive-date = 6 February 2012 | url-status = live }}</ref>
The colony of Western Australia (<abbr title="Western Australia">WA</abbr>) was commissioned in March 1831.<ref name="NAA1831">{{cite web | url = http://www.foundingdocs.gov.au/item.asp?dID=94 | title = Commission appointing Stirling Governor and Commander-in-Chief 4 March 1831 (UK) | work = Documenting a Democracy | publisher = National Archives of Australia | access-date = 2006-05-28 | url-status = dead | archive-url = https://web.archive.org/web/20080207042047/http://www.foundingdocs.gov.au/item.asp?dID=94 | archive-date = 7 February 2008 }}</ref>
From 1829 to 1832, the SRC/NSW border was at 129° east.
===1832–1836=== The name of the Swan River Colony was changed to Western Australia in 1832 (6 February 1832 – Map).<ref>Territorial evolution of Australia – 6 February 1832</ref>
From 1832 to 1846, 129° east was the <abbr title="Western Australia">WA</abbr>/<abbr title="New South Wales">NSW</abbr> border.
===1836–1846=== South Australia became a colony in 1836 and until 1846 would be surrounded on land by New South Wales (<abbr title="New South Wales">NSW</abbr>), with South Australia extending west to the 132° east longitude. (<abbr title="132nd meridian east longitude">132° east</abbr>) and north to <abbr title="26th parallel south latitude">26° south</abbr> (28 December 1836 – Map).<ref>Territorial evolution of Australia – 28 December 1836</ref>
From 1836 to 1846 <abbr title="129th meridian east longitude">129° east</abbr> was the <abbr title="Western Australia">WA</abbr>/<abbr title="New South Wales">NSW</abbr> border. <abbr title="132nd meridian east longitude">132° east</abbr> was the <abbr title="South Australia">SA</abbr>/<abbr title="New South Wales">NSW</abbr> border as were <abbr title="26th parallel south latitude">26° south</abbr> and <abbr title="141st meridian east longitude">141° east</abbr>.
===1846–1847=== In 1846 the colony of North Australia (<abbr title="North Australia">NA</abbr>) was proclaimed by Letters Patent, which was all of New South Wales north of <abbr title="26th parallel south latitude">26° south</abbr> (17 February 1846 – Map).<ref>Territorial evolution of Australia – 17 February 1846</ref>
From 1846 to 1847 <abbr title="129th meridian east longitude">129° east</abbr> was the <abbr title="Western Australia">WA</abbr>/<abbr title="New South Wales">NSW</abbr> border and the <abbr title="Western Australia">WA</abbr>/<abbr title="North Australian">NA</abbr> border. <abbr title="132nd meridian east longitude">132° east</abbr> was the <abbr title="South Australia">SA</abbr>/<abbr title="New South Wales">NSW</abbr> border, while <abbr title="26th parallel south latitude">26° south</abbr> became the <abbr title="South Australia">SA</abbr>/<abbr title="North Australia">NA</abbr> border and <abbr title="141st meridian east longitude">141° east</abbr> remained the <abbr title="South Australia">SA</abbr>/<abbr title="New South Wales">NSW</abbr> border.
===1847–1851=== In 1847 the colony of North Australia was revoked and reincorporated into New South Wales. (15 April 1847 – Map), so South Australia was once again surrounded by New South Wales on all land borders.<ref>Territorial evolution of Australia – 15 April 1847</ref>
From 1847 to 1860 <abbr title="129th meridian east longitude">129° east</abbr> was once again the <abbr title="Western Australia">WA</abbr>/<abbr title="New South Wales">NSW</abbr> border.
From 1847 <abbr title="132nd meridian east longitude">132° east</abbr> was again the <abbr title="South Australia">SA</abbr>/<abbr title="New South Wales">NSW</abbr> border, and <abbr title="26th parallel south latitude">26° south</abbr> was also the <abbr title="South Australia">SA</abbr>/<abbr title="New South Wales">NSW</abbr> border. <abbr title="141st meridian east longitude">141° east</abbr> would remain the <abbr title="South Australia">SA</abbr>/<abbr title="New South Wales">NSW</abbr> border until 1851.
===1851–1859=== In 1851 South Australia's eastern border changed again when the colony of Victoria was proclaimed (1 July 1851 – Map).<ref>Territorial evolution of Australia – 1 July 1851</ref>
From 1851 <abbr title="141st meridian east longitude">141° east</abbr> would change to include both the <abbr title="South Australia">SA</abbr>/<abbr title="New South Wales">NSW</abbr> border and the <abbr title="South Australia">SA</abbr>/<abbr title="Victorian">VIC</abbr> border.
===1859–1860=== In 1859 The colony of Queensland is proclaimed by Letters Patent, with its western border set at <abbr title="141st meridian east longitude">141° east</abbr><ref name="doc-s47">{{cite web | url=https://www.foundingdocs.gov.au/item-sdid-47.html | title=Letters Patent erecting Colony of Queensland 6 June 1859 (UK) | publisher=Museum of Australian Democracy | access-date=24 October 2017 | archive-url=https://web.archive.org/web/20171107015816/https://www.foundingdocs.gov.au/item-sdid-47.html | archive-date=7 November 2017 | url-status=live }}</ref> (6 June 1859 – Map).
From 1859 <abbr title="141st meridian east longitude">141° east</abbr> would change to include the <abbr title="South Australia">SA</abbr>/<abbr title="Queensland">QLD</abbr> border, the <abbr title="South Australia">SA</abbr>/<abbr title="New South Wales">NSW</abbr> border and the <abbr title="South Australia">SA</abbr>/<abbr title="Victorian">VIC</abbr> border.
===1860–1862=== In 1860 the western border of South Australia changed from <abbr title="132nd meridian east longitude">132° east</abbr> to <abbr title="129th meridian east longitude">129° east</abbr> (1860 – MAP).<ref>Territorial evolution of Australia – 1860</ref>
From this time on South Australia's western border was also the West Australian border.
From 1860 <abbr title="129th meridian east longitude">129° east</abbr> became the <abbr title="South Australia">SA</abbr>/<abbr title="Western Australia">WA</abbr> border from south of <abbr title="26th parallel south latitude">26° south</abbr> & the <abbr title="Western Australia">WA</abbr>/<abbr title="New South Wales">NSW</abbr> border north of <abbr title="26th parallel south latitude">26° south</abbr>.
===1862–1863=== In 1862 Queensland's western border north of <abbr title="26th parallel south latitude">26° south</abbr>) was moved to <abbr title="139th meridian east longitude">139° east</abbr> (1862).<ref>Territorial evolution of Australia – 1862</ref>
From 1862 <abbr title="26th parallel south latitude">26° south</abbr> became shared as the <abbr title="South Australia">SA</abbr>/<abbr title="New South Wales">NSW</abbr> border and the <abbr title="South Australia">SA</abbr>/<abbr title="Queensland">QLD</abbr> border between <abbr title="139th meridian east longitude">139° east</abbr> and <abbr title="141st meridian east longitude">141° east</abbr>.
===1863–1911=== In 1863 that part of New South Wales to the north of South Australia was annexed to South Australia by Letters Patent<ref name="doc-49">{{cite web | url=https://www.foundingdocs.gov.au/item-did-49.html | title=Letters Patent annexing the Northern Territory to South Australia, 1863 | publisher=Museum of Australian Democracy | access-date=24 October 2017 | archive-url=https://web.archive.org/web/20171107005903/https://www.foundingdocs.gov.au/item-did-49.html | archive-date=7 November 2017 | url-status=live }}<!-- Note: The webpage says that the territory was given a name, but the letter shown there does not mention any such name. --></ref> as "the Northern Territory of South Australia", which was shortened{{according to whom|date=May 2019}} to "the Northern Territory"<ref name="doc-49" /> (6 July 1863 – Map).
From 1863 to 1911 <abbr title="129th meridian east longitude">129° east</abbr> was the <abbr title="Western Australia">WA</abbr>/<abbr title="Northern Territory of South Australia">NToSA</abbr> border north of <abbr title="26th parallel south latitude">26° south</abbr> & the <abbr title="Western Australia">WA</abbr>/<abbr title="South Australia">SA</abbr> border south of <abbr title="26th parallel south latitude">26° south</abbr>. <abbr title="26th parallel south latitude">26° south</abbr> became the <abbr title="South Australia">SA</abbr>/<abbr title="Northern Territory of South Australia">NToSA</abbr> border.
===1911–1927=== In 1911 the Northern Territory was split off from South Australia to be administered by the Commonwealth. (1 January 1911 – Map).<ref>Territorial evolution of Australia – 1 January 1911</ref>
From 1911 to 1927 <abbr title="129th meridian east longitude">129° east</abbr> was the <abbr title="Western Australia">WA</abbr>/<abbr title="Northern Territory">NT</abbr> border north of <abbr title="26th parallel south latitude">26° south</abbr> & the <abbr title="Western Australia">WA</abbr>/<abbr title="South Australia">SA</abbr> border to the south. <abbr title="26th parallel south latitude">26° south</abbr> became the <abbr title="South Australia">SA</abbr>/<abbr title="Northern Territory">NT</abbr> border.
===1927–1931=== In 1927 the Northern Territory was split into two territories, North Australia and Central Australia, with the border set at the <abbr title="20th parallel south latitude">20° south</abbr>. (1 March 1927 – Map).<ref>Territorial evolution of Australia – 1 March 1927</ref>
From 1927 <abbr title="26th parallel south latitude">26° south</abbr> became the <abbr title="South Australia">SA</abbr>/<abbr title="Central Australia">CA</abbr> border.
===1931–Present=== In 1931 North Australia and Central Australia were reunited as the Northern Territory (12 June 1931 – Map).<ref>Territorial evolution of Australia – 12 June 1931</ref>
From 1931 <abbr title="26th parallel south latitude">26° south</abbr> once again became the <abbr title="South Australia">SA</abbr>/<abbr title="Northern Territory">NT</abbr> border.
==Marking the <abbr title="Northern Territory">NT</abbr> borders on the ground== Marking the Northern Territory borders on the ground has a fascinating history.
===Early attempts===
===Marking the <abbr title="Northern Territory">NT</abbr>/<abbr title="Western Australia">WA</abbr> border on the ground===
===Marking the <abbr title="Northern Territory">NT</abbr>/<abbr title="Queensland">QLD</abbr> border on the ground=== {{See|Queensland borders#Surveying the Queensland-Northern Territory border}}
===Marking the <abbr title="Northern Territory">NT</abbr>/<abbr title="South Australia">SA</abbr> border on the ground===
==The Northern Territory" border corners== {{coord|-26|129|region:AU|display=title}} thumb|Australia map with named state corners
===Surveyor Generals Corner=== {{main|Surveyor Generals Corner}} The West Australian border with the Northern Territory and South Australia, which has been marked on the ground, is not as straight as it looks, with the <abbr title="Western Australia">WA</abbr>/<abbr title="Northern Territory">NT</abbr> and <abbr title="Western Australia">WA</abbr>/<abbr title="South Australia">SA</abbr> borders being displaced by approximately 127 m, due to early survey errors within the limits of technology available in the 1920s.
The 127-metre section that runs east–west along the <abbr title="26th parallel south latitude">26° south</abbr> is part of the border between Western Australia and the Northern Territory. In June 1968, two monuments were erected to mark each end of this 127-metre sideways section; the easternmost of these monuments, being where all three borders meet, was named Surveyor Generals Corner.<ref>{{cite web|url=http://www.ga.gov.au/education/facts/dimensions/borders.htm |title=State and Territory Borders |date=11 September 2007 |publisher=Geoscience Australia |access-date=2008-07-13 |url-status=dead |archive-url=https://web.archive.org/web/20060102184417/http://www.ga.gov.au/education/facts/dimensions/borders.htm |archive-date=2 January 2006 }}</ref>
===Poeppel Corner=== {{main|Poeppel Corner}} Also known as Poeppels Corner in Queensland, at latitude 26° S and longitude 138° E, this is a corner of state boundaries, where the state of Queensland meets South Australia and the Northern Territory.
{{Auscorner}}
==See also== * Greenwich Time Signal
==References== {{reflist}}
==External links== * https://web.archive.org/web/20100618072942/http://www.ga.gov.au/education/geoscience-basics/dimensions/state-territory-borders.jsp
==External links== *{{cite web | title = 1921 WA-NT Border Determinations | publisher = Kununurra Historical Society Inc. (<abbr title="Kununurra Historical Society">KHS</abbr>), Kununurra, Western Australia | year = 2011 | url = http://www.kununurra.org.au/research/1921-wa-nt-border-determinations | access-date = 10 January 2012}} – This description of the 1921 Kimberley <abbr title="Western Australia">WA</abbr>/<abbr title="North Territory">NT</abbr> border determinations, involving SA Government Astronomer Dodwell, and <abbr title="South Australia">SA</abbr> Surveyors Hambidge and Maddern, along with the <abbr title="Western Australia">WA</abbr> Government Astronomer, Curlewis, mixes a news article with diary entries from M.P. Durack and photographs from the <abbr title="Kununurra Historical Society">KHS</abbr> Hambidge Collection. The <abbr title="Kununurra Historical Society">KHS</abbr> museum in Kununurra has a permanent display and archival material collected about the <abbr title="Western Australia">WA</abbr>/<abbr title="North Territory">NT</abbr> border & the <abbr title="Western Australia">WA</abbr>/<abbr title="South Australia">SA</abbr> border from which some of the research on this page has been based.
Category:Borders of Australia Category:Borders of South Australia Category:Borders of New South Wales Category:Borders of the Northern Territory Category:Borders of Queensland Category:Borders of Western Australia Category:History of the Northern Territory Category:Geography of the Northern Territory