The European Union -
Member States Timeline

1948

• January - Benelux customs union enters into force - economic grouping of Belgium, the Netherlands, and Luxembourg.
  January - GATT enters into force.
• March - Treaty of Brussels, creating the Western Union, signed by the governments of the United Kingdom, France, and the Benelux countries, pledging mutual military assistance in the event of an attack by Germany or Russia, while also seeking to foster greater economic, social, and cultural co-operation between the five states.

1949

• May 5 - Council of Europe, the first post-war political organization, established with the signing of the Treaty of London (Westminster) by ten European states - France, UK, Belgium, Netherlands, Luxembourg, Italy, Denmark, Ireland, Norway, and Sweden. Since it was given limited authority, it failed to become an organization with political power. (Although similar in name, The Council of Europe should not be confused with the later European Union bodies, the Council of the European Union or the European Council.)

1950

• May 9 - Schuman Declaration (Schuman Plan) - Plan announced by the French foreign minister, Robert Schuman, calling for the consolidation of coal and steel resources of France and West Germany under a common authority. Schuman's proposal would lead to the formation of the European Coal and Steel Community (ECSC) in 1951.
• June - Intergovernmental conference begins on the Schuman Plan proposals and negotiations to develop a plan for its implementation. Negotiations would lead to the signing of the Treaty of Paris in April 1951, which formally established the European Coal and Steel Community (ECSC)
• October - European Defence Community (EDC) draft draft initiative pubished. Although it would result in a draft treaty being signed in May 1952, the idea of forming a European Army was met with resistance and eventually abandoned in August 1954, when the French National Assembly refused to ratify it and voted it down.

European Coal and Steel Community

1951

• April 18 - Treaty of Paris establishing the European Coal and Steel Community (ECSC) signed. Formed by the six European states - Belgium, France, the Federal Republic of Germany (West Germany), Italy, Luxembourg, and the Netherlands. Would come into force on July 23, 1952. The ECSC would be officially disbanded on July 23, 2002.

1952

• May - European Defence Community (EDC) draft treaty signed by the six members of the European Coal and Steel Community (ECSC). The EDC was abandoned in August 1954 after the French National Assembly rejected it.
• July 23 - Treaty of Paris (European Coal and Steel Community Treaty) comes into effect.

1953

• March - Draft treaty of a European Political Community drawn up. The idea would be effectively abandoned in August 1954 when France refused to ratify the European Defence Community (EDC) treaty.

1954

• August - Plans for a European Political Community (EPC) and a European Defense Community (EDC) abandoned when France refused to ratify the European Defence Community (EDC) treaty.
• October - Western European Union (WEU) established when seven founding members signed a Protocol to the Treaty of Brussels (March 1948) agreement in Paris. Most of its military functions had been absorbed by the North Atlantic Treaty Organization (NATO) in 1949, and it served as more of an advisory body.

1955

• May - Western European Union (WEU) comes into operation, headquartered in London.
• June - Messina Conference - Meeting of the foreign ministers of the Six - the six founder members of the European Communities from the 1950 Schuman Plan - Belgium, France, the Federal Republic of Germany, Italy, Luxembourg, and the Netherlands - held in the Italian city of Messina, to consider new initiatives for European integration.

1956

• June - Negotiations open on the creation of the European Economic Community (EEC) and the European Atomic Energy Community (EAEC), also known as Euratom. The EEC and Euratom would be created with the signing of the Treaties of Rome in March 1957 and come into force in January 1958.

European Economic Community

1957

• March 25 - Treaty of Rome establishing the European Economic Community (EEC) signed in Rome. A separate document, also often referred to as the Treaty of Rome, establishing the European Atomic Energy Community (Euratom), was signed. The two documents are often referred to as the Treaties of Rome. Would come into force in January 1958.

1958

• January - Treaties of Rome (European Economic Community (EEC) Treaty and Euratom Treaty) come into force. The EEC structure consisted of four core institutions: the Council of Ministers, the Commission, the Parliamentary Assembly (European Parliament), and the Court of Justice.
• February - Benelux Economic Union Treaty signed in The Hague.

1960

• January 4 - Stockholm Convention signed establishing the European Free Trade Association (EFTA). Consisted of seven states - Austria, Denmark, Norway, Portugal, Sweden, Switzerland, and the United Kingdom.
• May - EFTA comes into force.
• November - Benelux Economic Union comes into force.

1961

• July - Ireland applies for EEC membership.
• July 31 - British Prime Minister Harold Maxmillan announces that the UK will apply for EEC membership.
• August - Britain and Denmark apply for EEC membership.

1962

• April - Norway applies for EEC membership.

1963

• January 14 - French President de Gaulle vetoes Britain's EEC membership.
• January 22 - Treaty of Friendship and Cooperation (Elysée Treaty) signed by France and the Federal Republic of Germany (West Germany). Pact was intended to create greater political cooperation and integration, particularly in four areas: defence, foreign affairs, education, and culture.

1965

• April 8 - Merger Treaty signed. Treaty formally integrated the executives of the European Atomic Energy Community (EAEC)(Euratom), the European Coal and Steel Community (ECSC), and the European Economic Community (EEC). Treaty created a single European Commission and a single Council of Ministers (officially the Council of Ministers of the European Communities). Treaty would come into effect on July 1, 1967.

1967

• May 11 - Second application for EEC membership by the UK.
• May - Second application for EEC membership by Denmark and Ireland.
• July - Norway applies for EEC membership.
• November 27 - Charles De Gaulle vetoes UK's second application for EEC membership.

1969

• December - Hague Summit - Leaders of the EEC SIX meet in The Hague agree on principles for enlargement, and the goal of an economic and monetary union. Pierre Werner, prime minister of Luxembourg, commissioned to prepare a report on Economic and Monetary Union.

1970

• June - Membership negotiations with the UK, Denmark, Ireland, and Norway resume. Will conclude in January 1972.

1972

• January - Membership negotiations with UK, Denmark, Ireland, and Norway conclude.
• May - Irish referendum approves EEC membership.
• September - Norway, in a referendum rejects EEC membership. Rejection was related to the recent discovery of massive oil reserves in the North Sea.
• October - Danish referendum approves EEC membership.

Nine

1973

• January 1 - Denmark, Ireland, and the UK join the European Communities. Brings membership to nine.

1975

• June - UK referendum on continued European Community (EC) membership.
• June - Greece applies for European Community (EC) membership.

1976

• June - Negotiations open on Greek European Community (EC) membership.

1977

• March - Portugal applies to join Community.
• July - Spain applies to join Community.

Ten

1981

• January 1 - Greece joins the European Communities, bringing membership to ten.

1982

• February - Greenland votes to leave the European Economic Community (EEC) .

Twelve

1986

• January 1 - Portugal and Spain join the European Community, bringing membership to twelve.

1987

• April - Turkey applies to join the European Community.

1989

• July - Austria applies to join the European Community.
• September - December - Collapse of communist governments in Eastern Europe.
• November 9 - Fall of the Berlin Wall.

1990

• June - Schengen Convention signed. Belgium, France, the Federal Republic of Germany, Luxwmbourg, and the Netherlands agree in principle to work towards the formation of a border-free Schengen Area. Agreement will be implemented in March 1995.
• June - Negotiations open on the creation of a European Economic Area (EEA). The EEA was a trading area composed of the members of the European Communities and members of the European Free Trade Association (essentially European countries who were not members of the European Community, but wanted to participate in the EC internal market).
• July - Cyprus and Malta apply to join the Community.
• October 3 - German reunification. East Germany (German Democratic Republic (GDR) unites with West Germany (Federal Republic of Germany))

Maastricht Treaty

1991

• July - Sweden applies to join the European Community.
• November - Negotiations on the creation of a European Economic Area (EEA) are completed.
• December - European Council, at the Maastricht summit, agrees to the Treaty on European Union (TEU)
• December 26 - Breakup of the Soviet Union. The Union of Soviet Socialist Republics (USSR) is officially dissolved.

1992

• February 7 - Representatives of the member states of the European Communities (EC) sign agreement, at Maastricht (The Netherlands), establishing a European Union. (While the title of the treaty was "Treaty Establishing a European Union," officially the organization was still the European Communities (EC).) The Maastricht Treaty will, after the Lisbon Treaty (2009), be renamed the Treaty on European Union (TEU). The Treaty establishing the European Community (the 1957 Treaty of Rome), with the Lisbon Treaty, will be renamed the Treaty on the Functioning of European Union (TFEU).
• March - Finland applies to join the European Union.
• May - Switzerland signs European Economic Area (EEA) membership agreement and applies to join the European Union.
• June 2 - Denmark holds referendum vote and rejects terms of the Maastricht Treaty.
• September 20 - French referendum on the Maastricht Treaty narrowly (51 per cent) approves.
• November - Norway applies again to join the European Union.
• December - Swiss referendum rejects membership of the European Economic Area (EEA). Swiss application for European Union membership suspended.

1993

• January - Single European market comes into force.
• February - Membership negotiations open with Austria, Finland, and Sweden.
• April - Membership negotiations with Norway.
• May - Second Danish referendum accepts terms of Maastricht.
• June - Copenhagen Criteria (accession criteria) adopted. The European Council, meeting in Copenhagen, Denmark adopt a set of conditions that the countries of Central and Eastern Europe must meet if they are to be admitted to the European Union. Generally, the criteria required that applicant states possess stable institutions which guarantee democracy, respect the rule of law and human and minority rights, possess a functioning free-market economy able to cope with competitive pressure and market forces, and be capable of meeting the obligations of EU membership.
• November 1 - Maastricht Treaty (Treaty on European Union) enters into force. The European Community institutions, the executives of the Europeam Atomic Energy Community, the European Coal and Steel Community, and the European Economic Community (EEC), which had been merged in April 1965, under the Merger Treaty, became one of three "pillars" of the European Union created by Maastricht. The other, (and new) pillars of intergovernmental co-operation, were the pillar of a "Common Foreign and Security Policy" and the pillar of "Justice and Home Affairs" (JHA). The Justice and Home Affairs pillar was renamed the "Police and Judicial Co-Operation in Criminal Matters" by the Treaty of Amsterdam in June 1997.

1994

• January - European Economic Area (EEA) comes into force, without Swiss participation. Switzerland had rejected EEA membership in a referendum in December 1992.
• March - Hungary applies to join the EU.
• April - Poland applies to join the EU.
• June - Referendum in Austria favors EU membership.
• October - Finnish referendum accepts EU membership.
• November - Swedish referendum accepts EU membership.
• November - Norwegian referendum rejects EU membership a second time.

Fifteen

1995

• January - Austria, Finland, and Sweden join the EU, bringing membership to fifteen.
• March - Schengen Agreement, originally signed on June 14, 1985 comes into force. The original Schengen Agreement had been signed in the town of Schengen, Luxembourg, on June 14, 1985 and was followed by the Schengen Convention, signed in June 1990 by the five founder members of the European Commuunity - Belgium, France, the Federal Republic of Germany, Luxembourg, and the Netherlands. The intent was to create a border-free Schengen Area allowing for the free movement of people. When the Agreement was implemennted in March 1995, it included the five original signatories, plus Portugal and Spain.
• June - Romania and Slovakia apply to join the European Union.
• October - December - Bulgaria, Estonia, Latvia, and Lithuania apply to join the European Union.

1996

• January - Czech Republic applies to join the European Union.
• June - Slovenia applies to join the European Union.

Treaty of Amsterdam

1997

• June - European Council agrees on the Treaty of Amsterdam. The fifteen heads of state and government reach agreement on measures combating high unemployment, extending citizens' rights, and improving democratic accountability and participation in the institutiions of the European Union.
• October - Treaty of Amsterdam signed. Following ratification by the member states, would come into force on May 1, 1999.

1998

• March - Negotiations on EU membership opened with Cyprus, Czech Republic, Estonia, Hungary, Poland, and Sovenia.

2000

• January - Negotiations on EU membership open with Bulgaria, Latvia, Lithuania, Malta, Romania, and Slovakia.

Treaty of Nice

2001

• February 26 - Treaty of Nice signed. In anticipation of the entry of smaller states from the former Eastern Bloc (Enlargement) the Nice Treaty made changes to the voting weight of member countries so that the larger population states, such as Germany, would maintain their representation.
• March - Swiss referendum rejects EU membership.
• June - Irish referendum rejects Treaty of Nice.

Constitutional Treaty

2002

• July 23 - Treaty of Paris, signed on April 18, 1951, creating the European Coal and Steel Community (ECSC) expires and the European Coal and Steel Community is officially disbanded. Established by the 1951 Treaty of Paris, in existence from July 23, 1952, after 1967, when its independent institutions were lost, it largely had only a semi-independent existence, with activities confined to regional issues of the coal and steel industries.
• October - Second Irish referendum approves Treaty of Nice.
• December - Copenhagen Summit formally approves the accession of the first 10 candidate countries to the EU. Cyprus, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia, and Slovenia will be accepted with the signing of the Treaty of Accession on April 16, 2003.

2003

• February 1 - Treaty of Nice, intended to prepare the European Union (EU) for enlargement, comes into force. Introduces a series of institutional reforms.
• March - September - Referendums in the Czech Republic, Estonia, Hungary, Poland, Latvia, Lithuania, Malta, Slovakia, and Slovenia approve EU membership. A referendum in Cyprus on an agreement to reunify the island, to be held in April 2004, is only approved by the southern half, with Greek Cypriots rejecting reunification.
• April 16 - Treaty of Accession, signed in Athens, Greece, admitting the 10 applicant states approved at the December 2002 Copenhagen Summit.

Twenty-Five

2004

• April - Greek Cypriots (northern half of island), in a referendum, reject agreement to reunify Cyprus. Southern half of the island accepts agreement.
• May - Ten countries, mainly Eastern European - Cyprus (southern half of island), the Czech Republic (Czechia), Estonia, Hungary, Poland, Slovenia, Latvia, Lithuania, Malta, and Slovakia - join the EU, bringing membership to twenty-five.

2005

• October - Negotiations on EU membership open with Croatia and Turkey.

Treaty of Lisbon

Twenty-Seven

2007

• January 1 - Bulgaria and Romania join the EU, bringing membership to twenty-seven.
• December 13 - Treaty of Lisbon - The new treaty is signed by the members meeting in Lisbon.

2009

• December 1 - Treaty of Lisbon enters into force. The treaty amends the 1992 Treaty on European Union (TEU) (Maastricht Treaty), which had been a revision of the 1957 Treaty of Rome. Although the 1992 Treaty on European Union (Maastricht) is considered the date when the European Union was formed, the Maastricht Treaty had used both the terms European Union and European Community. The Treaty of Lisbon retroactively replaced the term 'Community' with the term 'Union' so that, after Lisbon, the references in the treaties were to the 'European Union' rather then to the 'European Community.' The Treaty of Lisbon also renamed the 'Treaty Establishing the European Community' (EEC). It became the 'Treaty on the Functioning of the European Union' (TFEU). The European Economic Community (EEC) was the original title of the organization established by the 1957 Treaty of Rome treaties. The European Economic Community had originally been the European Coal and Steel Community (ECSC), formed by the Six founder members in the 1951 Treaty of Paris.

Twenty-Eight

2013

• July 1 - Croatia becomes the EU's twnty-eighth member state.
• November - Georgia and Moldova sign association agreements with the EU.

2015

• May - The Conservative Party under David Cameron wins an absolute majority in UK parliamentary elections and promises an "in-out" referendum on EU membership before the end of 2017.

2016

• June 23 - Brexit referendum vote in the UK. British electorate votes, by 51.9% to 48.1%, to leave the EU.
• June 24 - David Cameron announces his intention to resign as Prime Minister.
• July - Theresa May becomes UK prime minister and begins negotiations with the EU on the terms of the UK leaving the EU.
• November - High Court in the UK rules that government cannot invoke Article 50 of the Treaty of Lisbon, in order to leave the European Union, without being authorized by Parliament. Article 50 allows any member state of the European Union to withdraw from the European Union, so long as they comply with their constitutional requirements, and give the EU formal notice of their intention to withdraw.

2017

• March 25 - Sixtieth anniversary of the signing of the Treaty of Rome.
• March - British government gives European Union formal notice that it is invoking Article 50 of the Treaty of Lisbon to begin withdrawal process from the Union.
• April - EU leaders meet to discuss Brexit.
• November - European Council votes to relocate the European Banking Authority (EBA) from London to Paris and the European Medicines Agency (EMA) from London to Amsterdam, as a result of Brexit.

2018

• November - EU member states approve Theresa May's plan for Brexit.

2019

• April - UK Parliament refuses to approve Theresa May's plan for Brexit, resulting in a postponement of the date of Brexit.
• July - Theresa May resigns as prime minister, after UK Parliament refuses to approve a Brexit plan.
• December - Conservative Party wins a decisive majority in UK elections, after Boris Johnson vows to take the UK out of the EU.

Twenty-Seven

2020

• January 24 - Agreement signed by leaders of the Europeaan Union and the UK, finalizing UK leaving the EU (Brexit).
• January 31 - At midnight on January 31, the UK officially leaves the European Union, effectively out of the Union on February 1.