A customs union is a free trade zone with a common external tariff. That is, the same customs duties, quotas, preferences or other non-tariff barriers to trade apply to all goods entering the area, regardless of which country within the area they are entering. Purposes for establishing a customs union normally include increasing economic efficiency and establishing closer political and cultural ties between the member countries.
Examples of customs unions include the European Union, the EU-Turkey Customs Union, the Southern African Customs Union, the 1925 French Customs Union over Occupied Saarland, and the former Zollverein.
- Michael T. Florinsky. 1934. The Saar Struggle. New York: The Macmillan Company.