What event led to the US entering the war, why is that important? Can someone tell me the answer ??

On February 24, the British sent the Zimmerman telegram to President Wilson, and the United States press announced its presence on March 1. The news of the Zimmerman telegram outraged the American public, and it, along with Germany's resumption of submarine attacks, prompted the United States to enter the war.

Explanation:

answer; you can turn right on a red signal (when posted);