The United Nations officially came into existence in 1945.

In the late 19th century, countries began creating international organizations—organizations designed to enhance contact with and cooperation between the founding country and other countries in the world. In 1919 the League of Nations, one of the first truly "multinational" organizations, was founded. After the devastation wrought during World War I, the hope was that having a forum in which the countries of the world could debate and attempt to mediate conflict might prevent another such war. Those hopes were dashed by the start of World War II, and the League of Nations was disbanded. At the end World War II, another attempt was made to create such a forum. Representatives of 50 countries signed the charter for this new United Nations on June 26, 1945, and by October 24 the charter had been ratified by China, France, the Soviet Union, the United Kingdom, the United States and a majority of other countries. Today, there are 192 member countries, and the United Nations continues to work on a wide variety of civil, social and political issues of international concern. United Nations Day is celebrated on the 24th of October each year.

Xpeditions
In Unions and Alliances (3–5), students focus on the United Nations, learning about this organization’s functions and purposes and the broad geographical range of its members. Students then apply the concepts behind the UN’s mission to their own school, creating an alliance of students or school groups.

Students consider the potential impacts of transnational organizations such as the United Nations and the European Union in The Pros and Cons of Transnational Alliances (6–8).

In International Alliances (9–12), students discover the history, mission, function, and geographical range of six international alliances, including the United Nations.

The United Nations Foundation is one of several international organizations students read about as they investigate the conflict between the people of Darfur and the Janjaweed militia in What's Happening in Darfur? (6–8).

Among the many international conflicts that the United Nations attempts to resolve are disputes concerning natural resources, and very important among such resources are oil and water. In Oil and Water in the Middle East Region (6–8), students explore the roles of oil and water in the Middle East, especially in Iraq. Students use maps to look at the distribution of oil in the Middle East and discuss what it means for the different countries in the region. They also examine how water has influenced the region historically and politically.