How did the entry of the United States affect the outcome of the
World War I?

O boy, that’s a long, long, answer.

Well lets start.

First of all, why did the United States enter WWI?

There were a few reasons, but one sticks out the most... that is of course, money. The British and a few other countries the United States had funded were in fact, buying weapons and other supplies from the U.S. If the United States had just let these countries lose the war, they would have lost an insane amount of profits from these supplies that they had sent over. Therefore, the U.S. had a reason there. There are a few other arguements as to why, but for the general portion, that is widely considered the main reason the U.S. gto involved.

Moving on to your question: How did it effect the outcome of the war?

For starters, the war of WW1 was faught in the trenches, so the europeans were generally fighting for basically inches of land — that is until the Germans invented tanks and the infamous Blitzkrieg. The British and French forces were essentially being dominated by this overpowering force.

When the united States joined the war in 1917, it was a significant turn of events. The British and french now had access to additional resources, food, ammunition, the neccessities! The Americans also brought their people which added additional manpower to the fight.

So yes, the United States entering the war in 1917, definitely had an impact on WW1.