The United Nations established October 24 as the annual day to celebrate the creation of the UN Charter. It was created by General Assembly Resolution, A/RES/168 (II) on 31 October 1947. http://www.un.org/ga/search/view_doc.asp?symbol=A/RES/168%20(II)
On exhibit in the Green Library Lobby are a selection of materials from the Library's and Hoover Archives collections, including the UN Charter, reproductions of UN Day posters, and even a board game from 1955 titled: The United Nations and How It Works: Do It Yourself Kit.
Special thanks to Elga Zalite for her fantastic work on the exhibit and to the Hoover Archives for contributing materials.
For more information visit the UN Day Website, including the Resource page.