This is a list of referendums related to the European Union, or referendums related to the European Communities, which were predecessors of the European Union. Since 1972, a total of 48 referendums have been held by EU member states, candidate states, and their territories, with several additional referendums held in countries outside the EU. The referendums have been held most commonly on the subject of whether to become a member of European Union as part of the accession process, although the EU does not require any candidate country to hold a referendum to approve membership or as part of treaty ratification. Other EU-related referendums have been held on the adoption of the euro and on participation in other EU-related policies. The United Kingdom is the only country as an EU member state to have held referendums on continued membership of the European Union and its antecedent organisation, the European Communities. In the first referendum in 1975, continued membership of what was then the European Communities (which included the European Economic Community, often referred to as the Common Market in the UK) was approved by 67.2% of voters, while in its second referendum in 2016 voters voted by 51.9% to leave the European Union, effectively reversing the result of the first referendum. Greenland, an autonomous territory of Denmark, voted to leave the EC in a referendum in 1982 by 53% of voters. Summary EC enlargement of 1973 In 1972, four countries held referendums on the subject of the 1973 enlargement of the European Communities. — 1972 French European Communities enlargement referendum, 23 April 1972, 68.3% in favour, turnout 60.5% Before allowing the four new candidate member states to join the European Communities, founding member France held a referendum that approved this. Following the French approval, three of the four candidate states (Ireland, Denmark and Norway) likewise held referendums on the issue of joining the European Communities. The United Kingdom did not hold a referendum before joining. — a referendum to approve the Third Amendment of the Constitution of Ireland, 10 May 1972, 83.1% in favour, turnout 70.9% — 1972 Norwegian European Communities membership referendum, 25 September 1972, 53.5% against, turnout 79% Following the rejection by the Norwegian electorate, Norway did not join. — 1972 Danish European Communities membership referendum, 2 October 1972, 63.3% in favour, turnout 90.1% Denmark, Ireland, and the United Kingdom were admitted as members of the EC, acceding