Final answer:
The sinking of the Lusitania and the Zimmerman Note were pivotal events that pushed the United States into World War I due to public outrage and threats to national security.
Explanation:
The sinking of the Lusitania and the Zimmerman Note played crucial roles in bringing the United States into World War I. The sinking of the Lusitania in 1915, resulting in the death of 128 Americans, sparked outrage and public demand for war against the Triple Alliance. The Zimmerman Note, a revelation of a German-Mexican alliance plan against the U.S., further fueled the sentiment for war, leading President Woodrow Wilson to ask Congress for a declaration of war in April 1917.
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