In 1910, these countries held the Fourth International Conference of American States at Buenos Aires. They changed the name of the International Union of American Republics to the Union of American Republics. These countries held the ninth International Conference of American States between March and May 1948 at Bogotá. On 30th April 1948, 21 countries signed an agreement. They called this agreement the Charter of the Organization of American States. This was the beginning of the Organization of American States (OAS). OAS started functioning from December 1951.