Unrestricted submarine warfare ( the sinking of the British passenger ship the Lusitania)
American propaganda-
~As with the Spanish-American war american citizens over-exaggerated German cruelty. ~ Wanted Americans to support the war through neutrality
Zimmerman note- A message from Germany to Mexico intercepted by the British saying something along the lines of if you start fighting America once we win you will get Texas and New Mexico
The U.S. had business interests in European countries- America invested much money in the Allies (mainly Great Britain)