Why did the United States refuse to join the League of Nations after World War I?

The first meeting of the League of Nations in 1920 in Geneva, Switzerland

The League of Nations was an international organization, headquartered in Geneva, Switzerland, created after the First World War to provide a forum for resolving international disputes. Though first proposed by President Woodrow Wilson as part of his Fourteen Points plan for an equitable peace in Europe, the United States never became a member.

What was the League of Nations?

Speaking before the U.S. Congress on January 8, 1918, President Woodrow Wilson enumerated the last of his Fourteen Points, which called for a “general association of nations…formed under specific covenants for the purpose of affording mutual guarantees of political independence and territorial integrity to great and small states alike.” Many of Wilson’s previous points would require regulation or enforcement. In calling for the formation of a "general association of nations," Wilson voiced the wartime opinions of many diplomats and intellectuals on both sides of the Atlantic who believed there was a need for a new type of standing international organization.

He believed that this organization could be dedicated to fostering international cooperation, providing security for its members, and ensuring lasting peace. With Europe’s population exhausted by four years of total war, and with many in the United States optimistic that a new organization would be able to solve the international disputes that had led to war in 1914, Wilson’s articulation of a League of Nations was wildly popular. However, it proved exceptionally difficult to create, and Wilson left office never having convinced the United States to join it.

Why was the League of Nations Created?

The idea of the League was grounded in the broad, international revulsion against the unprecedented destruction of the First World War and the contemporary understanding of its origins. This was reflected in all of Wilson’s Fourteen Points, which were themselves based on theories of collective security and international organization debated amongst academics, jurists, socialists, and utopians before and during the war. After adopting many of these ideas, Wilson took up the cause with evangelical fervor, whipping up mass enthusiasm for the organization as he traveled to the Paris Peace Conference in January 1919, the first President to travel abroad in an official capacity.

Wilson used his tremendous influence to attach the Covenant of the League, its charter, to the Treaty of Versailles. An effective League, he believed, would mitigate any inequities in the peace terms. He and the other members of the “Big Three,” Georges Clemenceau of France and David Lloyd George of the United Kingdom, drafted the Covenant as Part I of the Treaty of Versailles. The League’s main organs were an Assembly of all members, a Council made up of five permanent members and four rotating members, and an International Court of Justice. Most important for Wilson, the League would guarantee the territorial integrity and political independence of member states, authorize the League to take “any action…to safeguard the peace,” establish procedures for arbitration, and create the mechanisms for economic and military sanctions.

Why did Republicans oppose joining the League of Nations?

President Woodrow Wilson

The struggle to ratify the Treaty of Versailles and the Covenant in the U.S. Congress helped define the most important political division over the role of the United States in the world for a generation. A triumphant Wilson returned to the United States in February 1919 to submit the Treaty and Covenant to Congress for its consent and ratification. Unfortunately for the President, while popular support for the League was still strong, opposition within Congress and the press had begun building even before he had left for Paris. Spearheading the challenge was the Senate majority leader and chairman of the Foreign Relations Committee, Henry Cabot Lodge.

Motivated by Republican concerns that the League would commit the United States to an expensive organization that would reduce the United States’ ability to defend its own interests, Lodge led the opposition to join the League. Where Wilson and the League’s supporters saw merit in an international body that would work for peace and collective security for its members, Lodge and his supporters feared the consequences of involvement in Europe’s tangled politics, now even more complex because of the 1919 peace settlement.

They adhered to a vision of the United States returning to its traditional aversion to commitments outside the Western Hemisphere. Wilson and Lodge’s personal dislike of each other poisoned any hopes for a compromise, and on March 1920, the Treaty and Covenant were defeated by a 49-35 Senate vote. Nine months later, Warren Harding was elected President on a platform opposing the League.


The United States never joined the League. Most historians hold that the League operated much less effectively without U.S. participation than it would have otherwise. However, even while rejecting membership, the Republican Presidents of the period, and their foreign policy architects agreed with many of its goals. To the extent that Congress allowed, the Harding, Coolidge, and Hoover administrations associated the United States with League efforts on several issues. Constant suspicion in Congress, however, that steady U.S. cooperation with the League would lead to de facto membership prevented a close relationship between Washington and Geneva.

Additionally, growing disillusionment with the Treaty of Versailles diminished support for the League in the United States and the international community. Wilson’s insistence that the Covenant be linked to the Treaty was a blunder; over time, the Treaty was discredited as unenforceable, short-sighted, or too extreme in its provisions, and the League’s failure either to enforce or revise it only reinforced U.S. congressional opposition to working with the League under any circumstances. However, the coming of World War II once again demonstrated the need for an effective international organization to mediate disputes, and the United States public and the Roosevelt administration supported and became founding members of the new United Nations.