When did the united states become involved in world war 1

Here is the answer to that and a bit more information as well:

World War 1, also known as the First World War (because it was named world war "1" so it shows that it is the first world war), or the Great War, was a global war specifically begging in Europe that lasted from 28 July 1914-11 November 1918. More than 70 million military personnel, including 60 million Europeans, were mobilized in one of the largest wars in history. Over nine million combatants and seven million civilians died as a result of the war, a casualty rate exacerbated by the belligerents' technological and industrial sophistication, and the tactical stalemate caused by grueling trench warfare. It was one of the deadliest conflicts in history, and paved the way for major political changes, including revolutions in many of the nations involved.

Here are some pictures for you to see/better understand.

Hope this helped! :D