Which three countries formed the Benelux Union in 1944?

The Benelux Union, also known as simply Benelux, is a politico-economic union and formal international intergovernmental cooperation of three neighboring states in western Europe: Belgium, Netherlands, and Luxembourg. The name Benelux is a portmanteau formed from joining the first two or three letters of each country's name (Belgium, Netherlands, Luxembourg) and was first used to name the customs agreement that initiated the union (signed in 1944). It is now used more generally to refer to the geographic, economic and cultural grouping of the three countries.

Since 1944, when a customs union was introduced, cooperation among the governments of Belgium, the Netherlands and the Grand Duchy of Luxembourg has been a firmly established practice. The initial form of economic cooperation expanded steadily over time, leading in 1958 to the signing of the Treaty establishing the Benelux Economic Union. Initially, the purpose of cooperation among the three partners was to put an end to customs barriers at their borders and ensure free movement of persons, goods and services among the three countries. It was the first example of international economic integration in Europe since the Second World War.