What annual observance marks the UN Charter's entry into force on 24 October 1945?

The annual observance marking the UN Charter’s entry into force on 24 October 1945 is United Nations Day. It commemorates the official creation of the United Nations and is observed every year on 24 October.

The UN Charter was adopted in San Francisco in June 1945, but it became legally effective later that year when the required ratifications were completed. The date therefore marks the organization’s formal beginning, not the signing ceremony itself. The first UN General Assembly declared 24 October an official commemorative day in 1947.

In 1971, the General Assembly adopted a resolution designating United Nations Day as an international observance and recommending that member states treat it as a public holiday. Events commonly include meetings, exhibitions, educational programs, cultural performances, and discussions about the UN’s work.

It is easy to confuse United Nations Day with other international observances, such as Human Rights Day on 10 December or World Development Information Day on 24 October. The latter shares the date, but United Nations Day specifically honors the UN Charter’s entry into force and the organization founded through it.