On March 26, 1991, the heads of state of Argentina, Brazil, Paraguay, and Uruguay gathered in the Paraguayan capital of Asuncion to sign a treaty formally establishing a regional economic integration initiative officially named the Southern Common Market, but better known as Mercosur. Thirty years on, the four countries remain active members and the association has plans for expansion. But what advantages has Mercosur brought to its founders? And what does the future hold for the bloc? Below, we consider…