What were the causes results of American entry into World War 1?

Answer 1

One of the cause of America entry into World War One was the announcement by Germany that there was unrestricted submarine warfare. The effect of America's entry is that it sped the end of the war.

Answer 2

The immediate cause of American entry into World War 1 was the German submarine warfare that targeted American ships. In addition, the interception and publication of the infamous Zimmermann Telegram, in which Germany proposed a military alliance with Mexico against the United States, further pushed the U.S. to join the war. American entry ultimately tipped the balance in favor of the Allies and led to their victory. Additionally, it accelerated social and political changes in the United States, as well as increased American influence on the world stage.