Why did the u.s. enter world war 1

Look for information on the "Zimmerman Note" that asked Mexico to attack the U.S. and the violation of the Sussex Pledge. Also look for history on the
Sinking of the Lusitania. Any more information would give you the direct answer and you need to research this a bit.

The United States Enters WWI
WikiAnswers - How and why did the US get involved in World War 1

Good evening Jackson 21...
I will just offer a simplified version of what happened. However, though I enjoy reading a lot about our American History, there will probably be somebody that can give you a more detailed answer.

I think it's important for you to know that we didn't want to enter the war in the first place and made that very clear. Our leaders looked at these problems as Europeon issues, not ours.

One big event that changed that was the sinking of the Lusitania. On that boat 1200 men died when it sank about 125 -128 of those men were Americans. Shortly after that the Germans sunk the Sussex, which enraged Americans.

Another reason that is still debated after all this time is our desire to get in there and help Britain which was in danger of being conquered. There are obvious reasons to protect them that still stands true today, when it comes to helping other countries. It opens the door, and keeps open the door, to strong economic and business ties and growth.

There are several other reasons politically the United States didn't want to look weak. They wanted to show they were not going to take this. Add that to dirt just thrown on their face, with the sinking of the boats, Britain under a lot of pressure, we no longer looked so neutral.

I hope this helps...