Northern Territory borders

Today the Northern Territory's land borders are defined to the west by the 129° east longitude (129° east ) with Western Australia, to the south by the 26th parallel south latitude (26° south ) with South Australia and to the east by 138° east longitude (138° east ) 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.

1788-1832
In 1788, Governor Phillip claimed the continent of Australia as far west as the 135th meridian east longitude (135° east ) in accordance with his commission. (26 January 1788 – Map)

On 16 July 1825, the western boundary of New South Wales was relocated to the line of 129° east to take in the new settlement at Melville Island. (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.

The colony of Western Australia (WA ) was commissioned in March 1831.

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).

From 1832 to 1846, 129° east was the WA /NSW border.

1836-1846
South Australia became a colony in 1836 and until 1846 would be surrounded on land by New South Wales (NSW ), with South Australia extending west to the 132° east longitude. (132° east ) and north to 26° south (28 December 1836 – Map).

From 1836 to 1846 129° east was the WA /NSW border. 132° east was the SA /<abbr title="New South Wales">NSW border as were <abbr title="26th parallel south latitude">26° south and <abbr title="141st meridian east longitude">141° east.

1846-1847
In 1846 the colony of North Australia (<abbr title="North Australia">NA ) was proclaimed by Letters Patent, which was all of New South Wales north of <abbr title="26th parallel south latitude">26° south (17 February 1846 – Map).

From 1846 to 1847 <abbr title="129th meridian east longitude">129° east was the <abbr title="Western Australia">WA /<abbr title="New South Wales">NSW border and the <abbr title="Western Australia">WA /<abbr title="North Australian">NA border. <abbr title="132nd meridian east longitude">132° east was the <abbr title="South Australia">SA /<abbr title="New South Wales">NSW border, while <abbr title="26th parallel south latitude">26° south became the <abbr title="South Australia">SA /<abbr title="North Australia">NA border and <abbr title="141st meridian east longitude">141° east remained the <abbr title="South Australia">SA /<abbr title="New South Wales">NSW 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.

From 1847 to 1860 <abbr title="129th meridian east longitude">129° east was once again the <abbr title="Western Australia">WA /<abbr title="New South Wales">NSW border.

From 1847 <abbr title="132nd meridian east longitude">132° east was again the <abbr title="South Australia">SA /<abbr title="New South Wales">NSW border, and <abbr title="26th parallel south latitude">26° south was also the <abbr title="South Australia">SA /<abbr title="New South Wales">NSW border. <abbr title="141st meridian east longitude">141° east would remain the <abbr title="South Australia">SA /<abbr title="New South Wales">NSW 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).

From 1851 <abbr title="141st meridian east longitude">141° east would change to include both the <abbr title="South Australia">SA /<abbr title="New South Wales">NSW border and the <abbr title="South Australia">SA /<abbr title="Victorian">VIC 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 (6 June 1859 – Map).

From 1859 <abbr title="141st meridian east longitude">141° east would change to include the <abbr title="South Australia">SA /<abbr title="Queensland">QLD border, the <abbr title="South Australia">SA /<abbr title="New South Wales">NSW border and the <abbr title="South Australia">SA /<abbr title="Victorian">VIC border.

1860-1862
In 1860 the western border of South Australia changed from <abbr title="132nd meridian east longitude">132° east to <abbr title="129th meridian east longitude">129° east (1860 – MAP).

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 became the <abbr title="South Australia">SA /<abbr title="Western Australia">WA border from south of <abbr title="26th parallel south latitude">26° south & the <abbr title="Western Australia">WA /<abbr title="New South Wales">NSW border north of <abbr title="26th parallel south latitude">26° south.

1862-1863
In 1862 Queensland's western border north of <abbr title="26th parallel south latitude">26° south ) was moved to <abbr title="139th meridian east longitude">139° east (1862).

From 1862 <abbr title="26th parallel south latitude">26° south became shared as the <abbr title="South Australia">SA /<abbr title="New South Wales">NSW border and the <abbr title="South Australia">SA /<abbr title="Queensland">QLD border between <abbr title="139th meridian east longitude">139° east and <abbr title="141st meridian east longitude">141° east.

1863-1911
In 1863 that part of New South Wales to the north of South Australia was annexed to South Australia by Letters Patent as "the Northern Territory of South Australia", which was shortened to "the Northern Territory" (6 July 1863 – Map).

From 1863 to 1911 <abbr title="129th meridian east longitude">129° east was the <abbr title="Western Australia">WA /<abbr title="Northern Territory of South Australia">NToSA border north of <abbr title="26th parallel south latitude">26° south & the <abbr title="Western Australia">WA /<abbr title="South Australia">SA border south of <abbr title="26th parallel south latitude">26° south. <abbr title="26th parallel south latitude">26° south became the <abbr title="South Australia">SA /<abbr title="Northern Territory of South Australia">NToSA border.

1911-1927
In 1911 the Northern Territory was split off from South Australia to be administered by the Commonwealth. (1 January 1911 – Map).

From 1911 to 1927 <abbr title="129th meridian east longitude">129° east was the <abbr title="Western Australia">WA /<abbr title="Northern Territory">NT border north of <abbr title="26th parallel south latitude">26° south & the <abbr title="Western Australia">WA /<abbr title="South Australia">SA border to the south. <abbr title="26th parallel south latitude">26° south became the <abbr title="South Australia">SA /<abbr title="Northern Territory">NT 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. (1 March 1927 – Map).

From 1927 <abbr title="26th parallel south latitude">26° south became the <abbr title="South Australia">SA /<abbr title="Central Australia">CA border.

1931-Present
In 1931 North Australia and Central Australia were reunited as the Northern Territory (12 June 1931 – Map).

From 1931 <abbr title="26th parallel south latitude">26° south once again became the <abbr title="South Australia">SA /<abbr title="Northern Territory">NT border.

Marking the <abbr title="Northern Territory">NT borders on the ground
Marking the Northern Territory borders on the ground has a fascinating history.

Marking the <abbr title="Northern Territory">NT /<abbr title="Western Australia">WA border on the ground
See <abbr title="Northern Territory">NT /<abbr title="Western Australia">WA border marking history

Surveyor Generals Corner
The actual 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 title="Northern Territory">NT and <abbr title="Western Australia">WA /<abbr title="South Australia">SA 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 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.

Poeppel Corner
Poeppel Corner (known as Poeppels Corner in Queensland) at latitude 26° S and longitude 138° E is a corner of state boundaries in Australia, where the state of Queensland meets South Australia and the Northern Territory.