IN January, 1960, the State Department of the United States issued formal invitations to countries and foreign organizations to participated in the World's Fair. By May 8th, 1961 the Organization of American States had accepted the invitation. Established in 1948, the Organization of American States (Oasis an international organization that brings together the independent countries of the Americas to promote cooperation, democracy, human rights, security and development. Its current membership includes 35 independent countries of North America, Central America, South America, and the Caribbean. The participation of some countries has varied over time.

The arch was meant to symbolize the goals of the Organization. Spanning the Fair's Avenue of the Americas, it would also symbolize the unity and friendship of the nations of the Western Hemisphere. The arch was designed by architect Stephen J. Kagel. The last mention of the arch appears in the World's Fair Progress Report of April 22, 1963 where it is still listed as an exhibit. Like many other proposed exhibits for the Fair, the Arch of the Americas faded away.

Miraculously, strangely or coincidentally, a remarkably similar arch, designed by Walter C. Harry, was constructed in Miami, Florida in 1965! This arch stands at the intersection of Northwest 167th Street and Northwest 13th Avenue in Miami. It has been recorded that the inspiration for the arch came from the St. Louis Gateway Arch. However the similarity between it and the Arch of the Americas is undeniable. Locals call it the "Modernage Arch" because it marked the entrance to a Modernage furniture store and the Sunshine State Industrial Park. It was designated as a historical site by Miami-Dade County in 2011.