United Nations Day was established by Presidential Proclamation（总统令） to commemorate the establishment of the United Nations in 1945.

It is celebrated very generally in all states and American possessions, and by all eighty-one countries, which are members of the United Nations for the purpose of informing the people of the world as to the aims, purposes, and achievements of the UN.

The name "United Nations" was devised by United States President Franklin D. Roosevelt and was first used in the "Declaration by United Nations" of January 1, 1942, during the Second World War, when representatives of 26 nations pledged their governments to continue fighting together against the Axis Powers（轴心国）.

The representatives of 50 countries at the United Nations Conference drew up the United Nations Charter（联合国宪章） on International Organization, which met at San Francisco from April 25 to June 26, 1945. Those delegates deliberated on the basis of proposals worked out by the representatives of China, the Soviet Union, and United Kingdom in the United States at Dumbarton Oaks（敦巴顿橡树园，在美国首都华盛顿效区） from August to October of 1944. The representatives of the 50 countries signed the Charter on June 26, 1945. Poland, which was not represented at the Conference, signed it later and became one the original 51 Member States.

The United Nations officially came into existence on October 24, 1945, when the Charter had been ratified by China, France, The Soviet Union, the United Kingdom, United States and by a majority of other signatories. United Nations Day is celebrated on October 24 each year.

In order to stress the charter's importance, in 1947 the General Assembly of the U.N. passed a resolution that October 24 shall hereafter（从此以后） be officially called United Nations Day, and shall be devoted to making known to the people of the world the aims and achievements of the United Nations, and to gaining their support for the work of the United Nations.

It was apparent, and also quite important, that the general public should be informed about the content and purposes of the United Nations; therefore an entire week-United Nations Week-was set aside in October, with its chief observance（庆祝） on United Nations Day, October 24.

By 1956, the American committee for the United Nations promoted the celebration of United Nations week. The official American Association for the United Nations sent out information and suggestions for programs with this advice: This is United Nations Week. The success of the United Nations in building world peace depends on all of us-on our won understanding and support; know how it works, and what it is doing. Help the United Nations help all of us to a peaceful future.

In some towns there is a public rally（集会）, perhaps at the City Hall, with the Stars and Stripes displayed with the flag of the United Nations. Speakers stress the accomplishments of the organization. Some shop windows feature products and dress of other lands. A town may put on an "International Festival" with songs and dances. During the week there are forums and panel discussions. An enjoy blending for United Nations Day is a banquet with foreign dishes.

An important part of the week's observance is the setting up of information centers, where literature on the work of the United Nations may be obtained.