The entrance of the United States into World War I was a very significant event. The fighting in World War I had been going since the summer of 1914. By April of 1917, when the United States entered the war on the side of the Allies, neither side was making progress. Both sides in the war had suffered heavy casualties. Morale was low, as few people had believed the war would last this long, and it appeared there was no end in sight.
When the United States entered the war, it was a huge help to the Allies. The American soldiers were rested and brought energy to the Allies. The spirit of the Allied soldiers improved significantly. Unites States industries produced much-needed supplies for the Allies. Military equipment and food were provided to assist the Allies in their fight against the Central Powers.
World War I was essentially at a stalemate until the United States entered the war. The entrance of the United States into the war gave the Allies the edge they needed to defeat the Central Powers.