This telegram, written by German Foreign Secretary Arthur Zimmermann, is a coded message sent to Mexico, proposing a military alliance against the United States. The obvious threats to the United States contained in the telegram inflamed American public opinion against Germany and helped convince Congress to declare war against Germany in 1917.
General Records of the Department of State; Record Group 59; National Archives.
Quelle:
Our Documents: 100 Milestone Documents from the National Archives
http://www.ourdocuments.gov/doc.php?doc=60
Das Original befindet sich im Politischen Archiv des Auswärtigen Amtes, Berlin.