The European Union (EU) is a political and economic union of 27 member states that are located primarily in Europe. Its members have a combined area of 4,233,255.3 km2 (1,634,469.0 sq mi) and an estimated total population of about 447 million. The EU has developed an internal single market through a standardised system of laws that apply in all member states in those matters, and only those matters, where members have agreed to act as one. EU policies aim to ensure the free movement of people, goods, services and capital within the internal market; enact legislation in justice and home affairs; and maintain common policies on trade, agriculture, fisheries and regional development. Passport controls have been abolished for travel within the Schengen Area. A monetary union was established in 1999, coming into full force in 2002, and is composed of 19 EU member states which use the euro currency. The EU has often been described as a sui generis political entity (without precedent or comparison).
A cartogram depicting the population distribution between old EU-27 member states (including the UK and excluding Croatia). 58% of all citizens of the EU live in the four largest member states: Germany, France, Italy, and Spain.
After two devastating world wars, the political climate favoured an international unity that could preserve peace in Europe effectively. (Hamburg, after a massive Alliedbombing in 1943 in the picture)
Map showing the population density by NUTS3 region, 2017, before Brexit