 These high-level summit meetings have been organized by a number of multilateral bodies under the aegis of the Organization of American States.In the early 1990s, what were formerly "ad hoc" summits came to be institutionalized into a regular "Summits of the Americas" conference program.In light of the economic and political challenges many countries in the region had faced since the 2001 Quebec City Summit of the Americas and because 14 Heads of State and Government in the Hemisphere had assumed office since then, the Government of Canada proposed holding a Special Summit of the Americas to reinforce hemispheric unity before the Fourth Summit of the Americas, which took place in Mar del Plata, Argentina, in 2005.