Republic of Ireland–United Kingdom border
| Republic of Ireland–United Kingdom border | |
|---|---|
A map showing the border | |
| Characteristics | |
| Entities | Republic of Ireland, United Kingdom |
| Length | 499 km (310 mi) |
| History | |
| Established | 3 May 1921 Government of Ireland Act 1920 (Partition of Ireland) |
| Current shape | 7 December 1922 Northern Ireland opt out of the Free State |
| Treaties | Anglo-Irish Treaty Northern Ireland Protocol (as part of the Brexit Withdrawal Agreement) |
| Notes | Open border not officially marked by either government |
The Republic of Ireland–United Kingdom border, sometimes referred to as the Irish border or British–Irish border, runs for 499 km (310 mi) from Lough Foyle in the north-west of Ireland to Carlingford Lough in the north-east, separating the Republic of Ireland from Northern Ireland.
Border markings are inconspicuous, in common with many inter-state borders in the European Union. As the two states share a Common Travel Area and (as of 2021) Northern Ireland (the only exception within the UK and only in some respects) and the Republic of Ireland are participants in the European Single Market, the border is essentially an open one, allowing free passage of people since 1923 and of goods since 1993. There are about 270 public roads that cross the border. Following the United Kingdom's exit from the European Union, this border is also the frontier between the EU and a non-member country. The Brexit withdrawal agreement commits all involved parties to maintaining an open border in Ireland, so that (in many respects) the trade frontier is the Irish Sea between the two islands. This de facto division of the United Kingdom is described, especially by Unionists, as "the Irish Sea border".