Proposals for a joint South American region cooperation network had circulated since the formation of the new independent South American countries. The revolutionary Simon Bolivar wanted a South American league of countries to counterbalance both Europe and the United States. States entered and re-entered into more local alliances, the largest of which created a free-trade zone around most of the eastern portion of the continent.

On this day, March 26, in 1991, the countries of Argentina, Brazil, Paraguay and Uruguay, together between them containing 267 million people over 5 million sq. mi. of land, signed the Treaty of Asuncion and established their common market.

Today the organization expanded to 10, with a pending full member and five associated member in Bolivia, Chile, Colombia, Ecuador and Peru. The association’s economic output expanded to $2.9 trillion in 2008, making it the fifth largest economy, by GDP, in the world.