United States. President (1945-1953 : Truman), Harry S. Truman (1961). “Harry S. Truman: Containing the Public Messages, Speeches, and Statements of the President, 1945-53”
First Inaugural Address, 4 Mar. 1933. According to Hans Sperber and Travis Trittschuh, American Political Terms: An Historical Dictionary, Herbert Hoover prominently used the term "good neighbor" during his tour of South America after the 1928 presidential election.