Humanities › Geography Countries in the European Union Share Flipboard Email Print H?kan Dahlstr?m/Getty Images Geography Basics Physical Geography Political Geography Population Country Information Key Figures & Milestones Maps Urban Geography By Matt Rosenberg Geography Expert M.A., Geography, California State University - Northridge B.A., Geography, University of California - Davis Matt Rosenberg is an award-winning geographer and the author of "The Handy Geography Answer Book" and "The Geography Bee Complete Preparation Handbook." our editorial process Matt Rosenberg Updated January 11, 2020 Formed in 1958 the European Union is an economic and political union between 28 member countries. It was created after World War II as a way to ensure peace between European nations. These countries share a common currency called the Euro. Those who reside in EU countries are also granted EU passports, which allow for easy travel between nations. In 2016, Brittain shocked the world by choosing to leave the EU. The referendum was known as Brexit. The Treaty of Rome The treaty of Rome is seen as the formation of what is now called the EU. Its official name was the Treaty Establishing the European Economic Community. It created a single market across the nations for goods, labor, services, and capital. It also proposed a reduction in customs duties. The treaty sought to strengthen the economies of the nations and to promote peace. After two World Wars, many Europeans were eager for peaceful alliances with their neighboring countries. In 2009 the Treaty of Lisbon would officially change the Treaty of Rome's name to The Treaty on the Functioning of the European Union. Countries in the European Union Austria: Joined in 1995Belgium: Joined in 1958Bulgaria: Joined in 2007Croatia: Joined in 2013Cyprus: Joined in 2004Czech Republic: Joined in 2004Denmark: Joined in 1973Estonia: Joined in 2004Finland: Joined in 1995France: Joined in 1958Germany: Joined in 1958Greece: Joined in 1981Hungary: Joined in 2004Ireland: Joined in 1973Italy: Joined in 1958Latvia: Joined in 2004Lithuania: Joined in 2004Luxembourg: Joined in 1958Malta: Joined in 2004Netherlands: Joined in 1958Poland: Joined in 2004Portugal: Joined in 1986Romania: Joined in 2007Slovakia: Joined in 2004Slovenia: Joined in 2004Spain: Joined in 1986Sweden: Joined in 1995United Kingdom: Joined in 1973. For the moment the UK remains a full member of the EU, however, it is in the process of withdrawing membership. Countries Integrating into the EU Several countries are in the process of integrating or transitioning into the European Union. Membership in the EU is a long and difficult process, it also requires a free-market economy and a stable democracy. Countries must also accept all the EU legislation, which can often take years to accomplish. AlbaniaMontenegro SerbiaThe Former Yugoslav Republic of MacedoniaTurkey Understanding Brexit On June 23, 2016, the United Kingdom voted in a referendum to leave the EU. The popular term for the referendum was Brexit. The vote was very close, 52% of the country voted to leave. David Cameron, then Prime Minister, announced the results of the vote along with his resignation. Teresa May would take over as Prime Minister. She promoted the Great Repeal Bill, which would repeal the country's legislation and incorporation into the EU. A petition calling for a second referendum received almost four million signatures but it was rejected by the government. The United Kingdom is set to leave the European Union by April 2019. It will take nearly two years for the country to sever its legal ties to the EU.