At a conference in San Francisco, delegates from 50 nations signed a charter establishing the United Nations.

The United Nations Conference on International Organization (UNCIO), commonly known as the San Francisco Conference, was a convention of delegates from 50 Allied nations that took place towards the end of World War II, from 25 April to 26 June 1945 in San Francisco, California, United States. At this convention, the delegates reviewed and rewrote the Dumbarton Oaks agreements of the previous year. The convention resulted in the creation of the Charter of the United Nations, which was opened for signature on 26 June, the last day of the conference. The conference was held at various locations, primarily the War Memorial Opera House, with the Charter being signed on 26 June at the Herbst Theatre in the Veterans Building, part of the Civic Center. A square adjacent to the Civic Center, called "UN Plaza", commemorates the conference.