Organization of American States
Phone Number
1 (202) 370 5000
Washington, USA

The Organization of American States is the world’s oldest regional organization, dating back to the First International Conference of American States, held in Washington, D.C., from October 1889 to April 1890. That meeting approved the establishment of the International Union of American Republics, and the stage was set for the weaving of a web of provisions and institutions that came to be known as the inter-American system, the oldest international institutional system.

OAS brings together all 35 independent states of the Americas and constitutes the main political, juridical, and social governmental forum in the Hemisphere. In addition, it has granted permanent observer status to 69 states, as well as to the European Union (EU).


IGRAC and OAS have both been involved in the groundwater component of the Transboundary Water Assessment Programme (TWAP), a project that involved the assessment of 199 transboundary aquifers and 43 Small Island Developing States.