进步联盟
On February 12, 1965 President Johnson named Vaughn Assistant Secretary of State for Inter-American Affairs and the United States coordinator of the Alliance for Progress. The bureau was the single largest unit in the State Department with more than 600 employees in Washington and 2,000 more abroad. Vaughn was in charge of relations with the twenty Latin-American republics as well as Jamaica, Trinidad, and British Guinea. Vaughn's responsibilities included managing the Alliance for Progress and the office dealing with the Organization of American States. Vaughn also carried the title of United States Coordinator for the Alliance for Progress.