The Charter of the OAS (Bogotá, Colombia, 1948. EIF December 1951) (Amended by subsequent Protocols of Buenos Aires (1967, EIF 1970); of Cartagena de Indias (1985, EIF 1988); of Managua (1993, EIF 1996); of Washington (1992, EIF 1997).)
Article 1 "an order of peace and justice, to promote their solidarity, to strengthen their collaboration, and to defend their sovereignty, their territorial integrity, and their independence"
All 35 independent American states are members - and OAS has 70 participating Permanent Observers.
Related commentary
Subject searches to use in SOLO include
Organization of American States
Pan-Americanism
The Organization of American States (OAS) by 
The Organization of American States As the Advocate and Guardian of Democracy by 
The Transformation of the Organization of American States by