East Lothian (/ˈloʊðiən/; Scots: Aest Lowden; Scottish Gaelic: Lodainn an Ear) is one of the 32 council areas of Scotland, as well as a historic county, registration county and lieutenancy area. The county was called Haddingtonshire until 1921.

In 1975, the historic county was incorporated for local government purposes into Lothian Region as East Lothian District, with some slight alterations of its boundaries. The Local Government etc. (Scotland) Act 1994 later created East Lothian as one of 32 modern council areas. East Lothian lies south of the Firth of Forth in the eastern central Lowlands of Scotland. It borders Edinburgh to the west, Midlothian to the south-west and the Scottish Borders to the south. Its administrative centre and former county town is Haddington while the largest town is Musselburgh.

Haddingtonshire has ancient origins and is named in a charter of 1139 as Hadintunschira and in another of 1141 as Hadintunshire. Three of the county's towns were designated as royal burghs: Haddington, Dunbar, and North Berwick.

As with the rest of Lothian, it formed part of the Anglo-Saxon kingdom of Bernicia and later the Kingdom of Northumbria. Popular legend suggests that it was at a battle between the Picts and Angles in the East Lothian village of Athelstaneford in 823 that the flag of Scotland was conceived. From the 10th century, Lothian transferred from the Kingdom of England to the authority of the monarchs of Scotland. It was a cross-point in battles between England and Scotland and later the site of a significant Jacobite victory against Government forces in the Battle of Prestonpans. In the 19th century, the county is mentioned in the Gazetteer for Scotland as chiefly agricultural, with farming, fishing and coal-mining forming significant parts of the local economy.

Following the end of the Roman occupation of Britain, Lothian was populated by Brythonic-speaking Ancient Britons and formed part of the kingdom of the Gododdin, within the Hen Ogledd or Old North. In the 7th century, all of the Gododdin's territory fell to the Angles, with Lothian becoming part of the kingdom of Bernicia.

Bernicia united into the Kingdom of Northumbria which itself became part of the early Kingdom of England. Lothian came under the control of the Scottish monarchy in the 10th century.

The earliest reference to the shire of Haddington, or Haddingtonshire, occurred in the 12th century, in two charters issued by King David. The shire covered the eastern part of Lothian.

Haddingtonshire was heavily involved in several medieval and early modern conflicts and several fortified castles and buildings such as Dunbar Castle, Tantallon Castle and Dirleton Castle date from this period.

In the 12th and 13th centuries, the Palace of Haddington was one of the seats of the Kings of Scotland. King William the Lion of Scotland used the palace from time to time and it was the birthplace of Alexander II in 1198. The palace and town were burned and pillaged in 1216, by an English army under the command of King John of England. In 1296, the Battle of Dunbar was a decisive victory for the forces of Edward I of England against the forces of John Balliol, the Scottish king who was Edward's vassal.

Haddingtonshire was also the site of conflict during the war of the Rough Wooing, with many houses and villages burnt by the English in May 1544 after the sacking of Edinburgh, the Scottish defeat at the battle of Pinkie, Dunbar Castle burnt in 1548, and the siege of Haddington. Haddingtonshire lairds supported the English cause, including John Cockburn of Ormiston, Alexander Crichton of Brunstane, and Regent Arran demolished their houses.

During the War of the Three Kingdoms, another Battle of Dunbar took place in 1650 between Scottish Covenanter forces and the English Parliamentary forces under Oliver Cromwell. The Parliamentary forces were victorious and able to march on to take Edinburgh.

Following the Restoration of the monarchy, Glorious Revolution and Acts of Union, Jacobite forces conflicted with Government forces, with the main conflict taking place as part of the 1715 Rising and 1745 Rising. Under the command of Sir John Cope, the British Army met with the Jacobites under Charles Edward Stuart at the Battle of Prestonpans in the west of the county in September 1745, with the Jacobite side gaining a significant victory before being defeated at the Battle of Culloden in April 1746.

Haddingtonshire County Council was created in 1890 under the Local Government (Scotland) Act 1889, which established elected county councils across Scotland, taking over most of the functions of the Commissioners of Supply, which had been the main administrative body of the shire since 1667. The county council was based at County Buildings in Court Street, Haddington, which had been built in 1833 and also served as the county's sheriff court.

In April 1921 the county council voted to request a change of the county's name from Haddingtonshire to "East Lothian". The government agreed and brought the change into effect as part of the East Lothian County Buildings Order Confirmation Act 1921, which received royal assent on 8 November 1921. The act also transferred ownership of the County Buildings to the county council.

In 1975 under the Local Government (Scotland) Act 1973, Scotland's county councils were dissolved and a new system of regional and district councils was created. East Lothian District was created within the wider Lothian region. The district comprised the historic county of East Lothian plus the burgh of Musselburgh and the parish of Inveresk (which included Wallyford and Whitecraig) from the county of Midlothian.

When further reforms in 1996 moved Scotland to a system of 32 unitary local authorities, the modern council area of East Lothian was created.

East Lothian is predominantly rural. It has 40 miles (64 km) of coastline where the towns of Musselburgh, Prestonpans, Cockenzie and Port Seton, Longniddry, Gullane, North Berwick and Dunbar lie along the coast of the Firth of Forth. The coast has several headlands and bays, most notably Gosford Bay, Aberlady Bay, Gullane Point, Sandy Hirst, Tyne Mouth, Belhaven Bay, Barns Ness, Chapel Point and Torness Point. There are several small islands off the coast north of North Berwick, the largest of these being Fidra, Lamb, Craigleith and Bass Rock.

Only two towns are landlocked, Tranent and Haddington. To the south are the Lammermuir Hills along the boundary with Berwickshire; it is here that Meikle Says Law, the highest point in the county at 535 metres (1,755 ft), can be found. The River Tyne flows through Haddington and several of East Lothian's villages, reaching the Firth of Forth near Belhaven. The River Esk flows through Inveresk and Musselburgh where it empties at the north of the town into the Firth of Forth. Major bodies of water include Pressmennan Lake, the Whiteadder Reservoir, Hopes Reservoir, Stobshiel Reservoir and Lammerloch Reservoir.

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  Bass Rock off the coast of East Lothian
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  Orographical Map of East Lothian
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  The Whiteadder Reservoir
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  Bass Rock in the Firth of Forth
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  Traprain Law
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  Geological Map of East Lothian

The A1 road travels through East Lothian where it meets the Scottish Borders southbound and Edinburgh northbound. The A1 throughout East Lothian is dual carriageway and major junctions include Dunbar, Haddington, Tranent, Prestonpans and Musselburgh.

Starting in Leith, the A199 road also travels through East Lothian beginning at Musselburgh and passing through Wallyford, Tranent, Macmerry and Haddington before joining the A1 in West Barns.

Some non-primary routes in East Lothian are the A198, A1087, A6093 and A6137 roads.

East Lothian is served by eight railway stations: East Linton (opened December 2023), Dunbar and Musselburgh on the East Coast Main Line; and North Berwick, Drem, Longniddry, Prestonpans and Wallyford on the North Berwick Line. Rail service operators which travel through and stop at stations in the area include: ScotRail on both lines; and CrossCountry and London North Eastern Railway on the East Coast Main Line.

Bus operators in East Lothian are: Lothian Buses and its subsidiary East Coast Buses, Eve Coaches of Dunbar, Prentice of Haddington and Borders Buses. East Coast Buses is the main bus service provider connecting the towns and villages of East Lothian to Edinburgh. The company has depots in North Berwick and Musselburgh.

The population of East Lothian as of 2022 is 112,450. The fastest growing district in East Lothian is the Tranent, Wallyford and Macmerry ward which is expected to see its population of just over 20,000 increase to just under 30,000 by 2026.

Ethnic Group	2001		2011		2022
	Number	%	Number	%	Number	%
White: Total	89,433	99.27%	98,011	98.29%	108,844	96.94%
White: Scottish	79,942	88.74%	85,347	85.59%	89,252	79.49%
White: Other British	7,708	8.56%	9,244	9.27%	13,508	12.03%
White: Irish	547	0.61%	870	0.87%	1,186	1.06%
White: Gypsy/Traveller	–	–	13	–	61	0.05%
White: Polish	–	–	811	0.81%	1,492	1.33%
White: Other	1,236	1.37%	1,726	1.73%	3,341	2.98%
Asian, Asian Scottish or Asian British: Total	319	0.35%	955	0.96%	1,368	1.22%
Asian, Asian Scottish or Asian British: Indian	63	0.07%	275	0.28%	318	0.28%
Asian, Asian Scottish or Asian British: Pakistani	110	0.12%	288	0.29%	436	0.39%
Asian, Asian Scottish or Asian British: Bangladeshi	14	–	43	–	28	–
Asian, Asian Scottish or Asian British: Chinese	95	0.11%	209	0.21%	266	0.24%
Asian, Asian Scottish or Asian British: Asian Other	37	–	140	0.14%	323	0.29%
Black, Black Scottish or Black British	18	–	–	–	–	–
African: Total	31	–	179	0.18%	315	0.28%
African: African, African Scottish or African British	–	–	177	0.18%	38	–
African: Other African	–	–	2	–	279	0.25%
Caribbean or Black: Total	–	–	107	0.11%	99	0.09%
Caribbean	30	–	59	0.06%	46	–
Black	–	–	29	–	10	–
Caribbean or Black: Other	–	–	19	–	43	–
Mixed or multiple ethnic groups: Total	176	0.20%	363	0.36%	1,164	1.04%
Other: Total	81	0.09%	102	0.10%	496	0.44%
Other: Arab	–	–	74	0.07%	153	0.14%
Other: Any other ethnic group	–	–	28	–	339	0.30%
Total:	90,088	100.00%	99,717	100.00%	112,284	100.00%

In the 2014 Scottish independence referendum, a majority of voters in the East Lothian council area opted for Scotland to remain a part of the United Kingdom - with 61.72% casting their ballots for the Union and 38.28% voting for independence.

Lothian East is a constituency in the House of Commons, electing one Member of Parliament. It is one of only 4 UK Parliamentary Constituencies in Scotland which matches the boundaries of its Local Authority area. The other examples being Inverclyde, Moray, and Na h-Eileanan an Iar, East Lothian is one of the few UK Parliamentary Constituencies which fully covers the boundaries of its Council area.

The current MP for Lothian East is Douglas Alexander of the Labour Party, who has represented the constituency since the 2024 general election, replacing Alba Party MP, Kenny MacAskill.

Former UK Prime Minister Arthur Balfour was born on 25 July 1848 at Whittingehame House in what is now the Lothian East constituency.

2019 general election: East Lothian

Party		Candidate	Votes	%	±%
	SNP	Kenny MacAskill	21,156	36.2	+5.6
	Labour	Martin Whitfield	17,270	29.5	−6.6
	Conservative	Craig Hoy	15,523	26.5	−3.1
	Liberal Democrats	Robert O’Riordan	4,071	7.0	+3.9
	UKIP	David Sisson	493	0.8	+0.8
Majority			3,886	6.7	N/A
Turnout			58,513	71.7	+1.1
	SNP gain from Labour		Swing	+6.1

Most of East Lothian is in the East Lothian Scottish Parliament constituency and South Scotland region with the exception of Musselburgh which is in Midlothian North and Musselburgh and the Lothians region.

East Lothian Council is based in the historic county town of Haddington, with the council meeting at the Haddington Town House and offices at nearby at John Muir House. The unitary local authority contains six wards, electing 22 councillors.