America's entry into World War I had a significant impact on the outcome of the war. Prior to America's entry, the war had been largely stalemated on the Western Front, with neither side able to gain a decisive advantage. However, America's entry into the war provided a much-needed boost to the Allied powers, both in terms of manpower and resources. The American military, while inexperienced, was well-equipped and well-supplied, and its entry into the war helped to tip the balance in favor of the Allies.
In addition to providing a boost to the Allied powers, America's entry into the war also helped to hasten the end of the conflict. With the arrival of fresh American troops on the Western Front, the Allies were able to launch a series of offensives that eventually broke through the German lines and forced Germany to sue for peace. The Treaty of Versailles, which ended the war, was signed in June 1919, and it was largely the result of the Allied powers' victory on the battlefield.
Overall, America's entry into World War I had a decisive impact on the outcome of the conflict. Without America's intervention, it is possible that the war would have continued for several more years, with no clear winner emerging. However, with America's help, the Allied powers were able to secure a victory that would shape the course of world history for decades to come.