By the end of the 19th century, almost all the nations of the Americas had liberated themselves from colonial rule. 

This raised the issue of what level of co-operation should exist between these states to mutually benefit each other. 

To address this, the First International Conference of American States met, at the invitation of the United States, in Washington, DC, from October 1889 through April 1890, to consider measures that would preserve and promote the prosperity and welfare of the American States. 

Near the end of the conference, on April 14th 1890, the conference adopted a resolution forming the International Union of American Republics, now known as the Organization of American States (OAS).  The OAS is the world’s oldest regional organization. 

The original member countries include Argentina, Bolivia, Brazil, Chile, Colombia, Costa Rica, Cuba, the Dominican Republic, Ecuador, El Salvador, Guatemala, Haiti, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, the United States, Uruguay, and Venezuela.  

Since the OAS has expanded to include many Caribbean countries who gained independence in the 20th century. 

The International Union of American Republics designated April 14th as Pan American Day in 1930, and it was first observed the following year.  

Though the OAS includes 35 countries, Honduras is the only country who observes a public holiday to mark the events of 1890. Though if any country was going to observe it, maybe it is fitting that it is this most central of American states which played an important part during the Spanish Empire. 

Despite being the only country to observe Pan American Day, Honduras was suspended from the OAS from 2009 – 2011 as the other nations did not recognize the legitimacy of the Honduran government during that time.