European Union: History, Governance, and Economic Integration

The European Union (EU) is a unique supranational union—an international organization where member states cede some of their sovereignty to shared institutions—comprising 27 European countries. Guided by the motto "In Varietate Concordia" (United in Diversity), the EU aims to foster economic cooperation, political stability, and the protection of fundamental rights across the continent.

From its origins as a coal and steel partnership to its current status as a global economic powerhouse, the EU has evolved through a series of landmark treaties that have expanded its scope from simple trade to a complex system of shared laws and a common currency.

Map showing the member states of the European Union (clickable)

Key Facts

Gerald Ford and the American delegation at the CSCE (1975)

Membership: 27 member states.
De Facto Capital: Brussels, Belgium.
Population: Estimated 451,990,314 (2026).
Economy: Estimated nominal GDP of $23.035 trillion (2026).
Currency: The Euro (€), used by the majority of members (the Eurozone).
Official Languages: 24 official languages.
Land Area: Approximately 4,225,104 km², including outermost regions.

The Evolution of the Union

The ancient Roman Agora in Athens illuminated with a Next Generation EU sign

The EU was not created overnight but developed through a phased approach to integration, beginning in the aftermath of World War II to prevent future conflict.

Foundational Treaties

The journey began with the Treaty of Paris (1952), which established the European Coal and Steel Community (ECSC). This was followed by the Treaty of Rome (1958), which created the European Economic Community (EEC) and the European Atomic Energy Community (EAEC/EURATOM).

Signing ceremony of the Treaty of Rome (1957), establishing the EEC

Expansion and Modernization

The union underwent significant transformations through the Single European Act (1987) and the Maastricht Treaty (1993). The latter was pivotal, as it formally established the European Union and laid the groundwork for the single currency. The most recent major structural update was the Treaty of Lisbon (2009), which streamlined the EU's decision-making processes and strengthened its legal personality.

Maastricht Treaty (1992), establishing the EU

Signing ceremony of the Treaty of Lisbon (2007)

Governance and Political Structure

A schematic representation of the political system of the European Union, including realpolitik

The EU operates through a mixed supranational and intergovernmental system, meaning decisions are made both by independent EU bodies and by the governments of the member states.

Branches of Power

Executive: Led by the President of the European Commission (Ursula von der Leyen) and the President of the European Council (António Costa).
Legislative: Power is shared between the European Parliament (representing EU citizens) and the Council of the European Union (representing member state governments).
Judicial: The Court of Justice ensures that EU law is interpreted and applied consistently across all member states.

Organigram of the political system of the European Union

Competencies and Authority

The EU's authority is divided into three types of competence:

Exclusive Competence: Areas where only the EU can legislate, such as the customs union and monetary policy for Eurozone members.
Shared Competence: Areas where both the EU and member states can act, including the internal market, environment, and energy.
Supporting Competence: Areas where the EU supports member state actions, such as culture, tourism, and education.

Economic and Geographic Integration

Eastern Partnership Summit 2017, Brussels

The EU is characterized by deep economic integration designed to allow the free movement of goods, services, capital, and people.

The Single Market and Eurozone

The Single Market removes trade barriers between members, while the Customs Union establishes a common external tariff for non-EU countries. The Eurozone consists of those member states that have adopted the Euro as their sole legal tender.

Eurozone participation European Union member states(special territories not shown) Non–EU member states vte

European Single Market Non-EU states which participate

The Schengen Area

The Schengen Area is a zone where internal border checks have been abolished, allowing seamless travel. While most EU members participate, some have opt-outs; for example, Ireland maintains its own border controls due to its relationship with the UK.

Infrastructure and Resources

The EU manages massive infrastructure projects via the Trans-European Transport Network and maintains the world's largest exclusive economic zone (EEZ) at 25 million square kilometres.

Map of the Trans-European Transport Network

The EU's exclusive economic zone (EEZ). At 25 million square kilometres, it is the largest in the world.[241]

EU Summary Table

Union for the Mediterranean meeting in Barcelona

Overview of European Union Specifications
Category	Details
Member States	27 Countries
Primary Currency	Euro (€)
GDP (Nominal 2026 Est.)	$23.035 Trillion
Population (2026 Est.)	451,990,314
Main Institutional Seats	Brussels, Frankfurt, Luxembourg, Strasbourg
Key Legal Frameworks	Treaties of Rome, Maastricht, and Lisbon

Frequently Asked Questions

Map showing European membership of the EU and NATO EU member only NATO member only EU and NATO member

Topographic map of Europe (EU highlighted)

A Köppen–Geiger climate classification map of Europe (including non-EU member states)

Increase of average yearly temperature in selected cities in Europe (1900–2017)[183]

GDP (PPP) per capita (including non-EU countries)

European Customs Union Non-EU states which participate

EU free trade agreements European Union Agreement in force Agreement (in part) provisionally applied

Satellite photo of the Port of Rotterdam

Galileo control centre in Oberpfaffenhofen, Germany

Classification of regions from 2021 to 2027 Less developed regions Transition regions More developed regions

Map showing the population density by NUTS3 region, 2017, including non-EU countries

The Paris metropolitan area is the most populous urban area in the EU.

Erasmus of Rotterdam, the Renaissance humanist after whom the Erasmus Programme is named

The Charter of Fundamental Rights of the European Union contains a wide range of political, social, and economic rights for EU citizens.

Europa and the Bull on a Greek vase, c. 480 BC. Tarquinia National Museum, Italy.

The European emblem emblazoned on the Eiffel Tower

What is the difference between the EU and the Eurozone?

The European Union is the overall political and economic union of 27 member states. The Eurozone is a subset of the EU consisting only of those member states that have adopted the Euro as their official currency.

Which cities serve as the EU's institutional seats?

The EU distributes its institutions across several cities: Brussels (Commission, European Council, Council of the EU), Strasbourg (Parliament), Luxembourg (Court of Justice, Court of Auditors), and Frankfurt (European Central Bank).

What are "opt-outs" in the context of the EU?

Opt-outs are legal provisions that allow specific member states to exempt themselves from certain EU policies. For example, Denmark has an opt-out from the Eurozone, and Ireland has an opt-out from the Schengen Area.

How is the EU's budget allocated?

EU funding is distributed across several priorities. Based on 2014–2020 data, the largest shares went to Sustainable Growth/Natural Resources (38.6%) and Economic, Territorial, and Social Cohesion (34.1%).

What is the Schengen Area?

The Schengen Area is a region comprising several European countries (both EU and non-EU) that have officially abolished all passport and all other types of border control at their mutual borders.