This conference consisted of delegates from 50 allied nations. Its purpose was to create and adopt a charter for a new organization, the United Nations Organization.
United States President Franklin D. Roosevelt had died on April 12, 1945. Vice President Harry S. Truman became United States President, and the UNCIO conference was to commence April 25, 1945. United States delegates had not been appointed to the UNCIO conference and the new President had 13 days to appoint. He did so and additionally he had the State Department appoint US organizations to advise the US delegates. Forty-Two organizations were appointed:
Those were the original member organizations, and a few are still involved in the U.S. Council of Organizations to this day.