Supranationalism: The AMSCO book states, "The practice of multiple countries forming an organization for the benenfit of all members is supranationalism" (4.9).
Organizations Within El Salvador: El Salvador is a part of a major supranational organization, the UN. The UN offers security, protects human rights, and promotes peace. Their headquarters is located in NYC. 193 states are part of the UN. "Wikipedia" states, "El Salvador is a member of the United Nations and several of its specialized agencies, the Organization of American States (OAS), the Central American Common Market (CACM), the Central American Parliament (PARLACEN), and the Central American Integration System (SICA)" (Foreign Relations of El Salvador).