Editing Organization of American States (section)

===20th century===
[[File:Pan American Union, Washington, DC in 1943.jpg|thumb|[[Pan American Union Building|Pan American Union headquarters building]] in [[Washington, D.C.]] in 1943]]
At the fourth [[International Conference of American States]] ([[Buenos Aires]], 1910), the name of the organization was changed to the Union of American Republics and the Bureau became the Pan American Union. The [[Pan American Union Building]] was constructed in 1910, on [[Constitution Avenue]], [[Northwest, Washington, D.C.]]

In the mid-1930s, U.S. President [[Franklin Delano Roosevelt]] organized an inter-American conference in Buenos Aires. One of the items at the conference was a "[[League of Nations]] of the Americas", an idea proposed by Colombia, Guatemala, and the Dominican Republic.<ref>Special to the New York Times. [https://www.nytimes.com/1936/04/13/archives/league-of-nations-in-americas-urged-by-3-latin-states-this-is-one.html?sq=League+of+nations+in+Americas&scp=1&st=p "League of Nations in Americas urged by 3 Latin states"], ''The New York Times''. 13 April 1936. p. 1.</ref> At the subsequent Inter-American Conference for the Maintenance of Peace, 21 nations pledged to remain neutral in the event of a conflict between any two members.<ref>[https://www.nytimes.com/1936/12/20/archives/americas-adopt-neutrality-pact-21-nations-pledge-a-joint-attitude.html "Americas adopt neutrality pact"], ''The New York Times''. 20 December 1936.</ref> The experience of [[World War II]] convinced hemispheric governments that unilateral action could not ensure the territorial integrity of the American nations in the event of external aggression. To meet the challenges of global conflict in the postwar world and to contain conflicts within the hemisphere, they adopted a system of [[collective security]], the [[Inter-American Treaty of Reciprocal Assistance]] (Rio Treaty) signed in 1947 in [[Rio de Janeiro]].

The ninth [[International Conference of American States]] was held in [[Bogotá]] between March and May 1948 and led by [[United States Secretary of State]] [[George Marshall]], a meeting which led to a pledge by members to fight communism in the [[western hemisphere]].<ref>{{cite web |url = https://www.britannica.com/topic/Organization-of-American-States |title=Organization of American States |website=Encyclopedia Britannica|language=en|access-date=4 September 2019}}</ref> This was the event that saw the birth of the OAS as it stands today, with the signature by 21 American countries of the [[Charter of the Organization of American States]] on 30 April 1948 (in effect since December 1951). The meeting also adopted the [[American Declaration of the Rights and Duties of Man]], the world's first general human rights instrument.

The transition from the Pan American Union to OAS would have been smooth if it had not been for the assassination of Colombian leader [[Jorge Eliécer Gaitán]]. The Director General of the Pan American Union, [[Alberto Lleras Camargo]], became the Organization's first [[Secretary General of the Organization of American States|Secretary General]].