Parts of Wilson’s vision would find deep sympathies in the American political environment, like his call for free exchange of goods and the opening of the seas. The vision of the world economy as an open playing field and not as one controlled by parochial European interests announced the arrival of American economic and political power on the world stage. This notion, that America should be able to participate in an unfettered way in the world economy, would become a signature part of American identity. At the same time, the United States did not want to limit the flexing of its own interests and its ability to act. The 14th point that Wilson enumerated in his statement called for an international body to adjudicate between nations and settle disputes. All nations, Wilson believed, should place themselves under the protective umbrella of this world organization. This idea, which was Wilson’s passion, came together in the formation of the League of Nations. The U.S. Senate, however, objected to the idea of the League and rejected the treaty, sending a clear message to the ailing Wilson that autonomy, not consensus, would define the United States’ role in the world.
Autonomy should not be mistaken for isolationism. In the decade after the war, despite the U.S. Senate blocking the ratification of the Versailles Treaty (though a majority supported it), the United States continued the play a vital role in world affairs, a more active one than in the pre-WWI decades. Of primary importance to U.S. interests after WWI was the stability of Europe, and the United States negotiated multiple plans to deal with tensions between Germany and France with regard to German reparations, economic stability, and territorial occupation and sovereignty. The signature moment of U.S. participation in this regard was the negotiation of the Dawes Plan by Charles Dawes in 1924, for which Dawes was awarded the Nobel Peace Prize.
If it is the case that the United States was more involved in direct international negotiations and resolutions in the 1920s than before the war, why is it that the 1920s have become known for U.S. isolationism? This is partly because the U.S. did not enter the League of Nations, thus crippling what might have been an important international body for maintaining world peace. This stands in contrast to the U.S. role in the United Nations after WWII, an era defined by U.S. dominance of global affairs. Second, both xenophobia and economic protectionism became even stronger currents in U.S. policy and culture in the 1920s, resulting in the institution of protective tariffs and strict quotas designed to choke off immigration. Whatever was happening on the level of state relations, this gave U.S. culture in the 1920s a decidedly inward, nativist appearance. Third, the 1930s eventually cast a huge shadow back on the 1920s, as this decade did for many nations. The international failure to check Germany became the central issue of international affairs in the aftermath of WWII, and part of the dominant narrative is that the U.S. role in shaping the European balance of power in the 1930s was too passive, too hands-off. The powerlessness of the League of Nations, the breakdown of systematic international cooperation in the face of rising German militancy and aggression highlighted each specific policy breakdown. Finally, the narrative about U.S. isolationism in the 1920s created a rationale for the great expansion of U.S. power after WWII. The U.S. claim to be the guarantor of global stability was strengthened by comparing the U.S. led world order after 1945 with the disorder of the 1930s, which allowed for belligerent actors like Nazi Germany and Imperial Japan to act unchecked. Thus, the narrative of isolation in the 1920s and 1930s provided the U.S. with the "moral authority" it desired in its construction of the post-WWII order.