Why was it important for the US to enter World War 1?

Answer 1

That's an interesting question. For my money the better question is why didn't we enter sooner? To answer your question though, Americans were killed when they sunk the Lusitania. President Wilson still wouldn't ask Congress to declare war. Former President Roosevelt called him a coward, but even that wasn't enough. It took the sinking of several more subs and the deaths of many more AMerican's before Wilson finally asked Congress to declare war. For a better description see here. http://en.wikipedia.org/wiki/Ww1#Entry_of_the_United_States

Answer 2

American entry was important to WW1 because it showed other countries that they were not afraid to fight and that they were a strong country. It was also important because the U.S. helped the Allies win.