On Feb. 7, 1992, a landmark agreement was signed in the Dutch city of Maastricht by twelve member states — the Treaty on European Union. Widely referred to as the Maastricht Treaty, this historic document brought the European Union (EU) into existence, built upon a framework of three pillars. These included the European Communities (a renaming of what had previously been called the European Economic Community), a coordinated approach to foreign policies and security, and enhanced cooperation on justice and domestic affairs.
A new monetary union emerged from the Maastricht Treaty, laying the groundwork for what would eventually become a shared currency — the euro, as it is known today. The objectives behind this union were clear: maintain price stability, dismantle trade barriers, and establish guidelines (referred to as the Maastricht criteria) that both existing and prospective member states would need to follow in order to sustain economic health. Additionally, every citizen of the member nations received EU citizenship.
The twelve signatories to the treaty were the United Kingdom, Ireland, Belgium, Denmark, Spain, France, Germany, Greece, Luxembourg, the Netherlands, Italy, and Portugal. It wasn't until Nov. 1, 1993, however, that the treaty officially took effect. Denmark posed an early challenge — in June of 1992, Danish voters rejected a referendum on the treaty, driven by concerns about losing their sovereignty. They would go on to approve a revised version the following May. Meanwhile, the United Kingdom agreed to participate only after securing exemptions from the social policies and the adoption of the euro.
The EU has since grown to encompass 27 countries with over 440 million citizens. In 2016, the United Kingdom voted in a referendum to leave the EU, and after four years of negotiations, their departure became official on Jan. 31, 2020. To this day, they remain the only country to have left the EU.