Which 1991 treaty established Mercosur as a common market among Argentina, Brazil, Paraguay and Uruguay?

The 1991 Treaty of Asunción established Mercosur as a common market among Argentina, Brazil, Paraguay and Uruguay. It was signed on 26 March 1991 in Asunción, Paraguay.

The agreement aimed to remove customs duties and other trade barriers among its founding members, while developing a common external tariff for goods from outside the bloc. Its long-term goal was the free movement of goods, services, people and capital.

Mercosur’s name comes from Mercado Común del Sur, meaning “Common Market of the South.” Venezuela later joined as a full member, although its membership has been suspended, and Bolivia became a member in 2024. Chile, Peru, Colombia and other countries participate as associate members.

The Treaty of Asunción is often confused with the 1994 Protocol of Ouro Preto, which gave Mercosur its institutional structure and international legal personality.