What did the US contribute to World War I?

Even thought the United States was only involved in World War I for a little over a year, the country helped turn the tide of the war in favor of the Allies. By late 1917 and early 1918, over 2 million US Soldiers were serving in Europe providing badly needed reinforcements on the Western front. Since the Russians had pulled out of the war in late 1917, the Germans could now dedicate all of their troops to fighting against the Allies on the Western Front. British and French troops were exhausted and spent after 3.5 years of fighting and the Americans brought the manpower that they needed to win the war. Americans were successful in such pivotal battles such as the Battle of Belleau Wood in June 1917. In this significant battle, The American forces stopped a major German offensive push towards Paris. This battle was successful at driving the Germans back and weakening German morale.
America was already supplying our allies with supplies prior to our involvement in the war, so the arrival of fresh American troops is our greatest contribution.

The United States contributed a great deal to World War I. While there were many reasons why the United States sided with the Allied Powers in the war, the German decision to resume the use of unrestricted submarine warfare was an important factor, as Germany began to sink American ships without warning. At the time the United States joined the war, both the Allied Powers and the Central Powers were wearing down from the long and difficult conflict. On its entrance into the war, the United States provided well-rested troops for the Allies. The United States also provided essential supplies and military equipment to help the Allies, for which the Europeans had been previously paying. The United States also provided convoys to help its merchant marine travel across the Atlantic, and the American navy assisted Great Britain with the blockade of Germany. The effectiveness of this blockade significantly reduced Germany's ability to get needed supplies. Without the entrance of the United States into the war on the side of the Allies, an Allied victory would have been more difficult to achieve.