There were a few reasons why the United States Senate rejected the Treaty of Versailles after World War I ended. One reason was the concern that the Treaty of Versailles would force the United States to get involved in issues that had no relevance to the United States. The Treaty of Versailles created an organization called The League of Nations. This organization was designed to prevent future conflicts by providing an organizational body in which nations could settle any disputes they had with each other. It also was possible that the League of Nations could authorize actions against a nation if a nation did not comply with an order issued by the League of Nations. This might force the United States to have to do something that was not in the best interests of the country, such as taking economic actions against a country. Other people felt the country would get involved in foreign situations that would not be beneficial to the United States.

Some members of the United States Senate, led by Henry Cabot Lodge, wanted to make some changes to the Treaty of Versailles, President Wilson, who disliked Henry Cabot Lodge, refused to consider any changes. Neither party was ultimately willing to compromise. Without any changes, the United States Senate refused to ratify the Treaty of Versailles .