League of Nations
The League of Nations was an international organization, existing from 1919 to 1946. The League was created by the the Allied and neutral nations after World War I, to safeguard against future conflict. After World War II, The League of Nations was dissolved to make way for the UN.
The United States never formally joined the League of Nations. The primary reason for the absence of the United States in the League of Nations was that the American public thought that it was another way of getting entangled in European affairs. This idea was best represented when President Woodrow Wilson, a strong advocate for the League of Nations, attempted to ratify the League of Nations Charter via the United States Congress which resulted ultimately in a failing vote.