What factors/events eventually influence the US to enter the great war?

The first factor or event that eventually lead to the United States entering World War I was the sinking of the Lusitania. This was a ship that was sunk by Germans in 1915, and killed over 100 Americans and over 1,000 overall passengers onboard. This was the first factor that lead the United States to join World War I, but it was not the biggest one. The biggest factor that caused the U. S. to join into World War I was the Zimmerman Telegram. This telegram was from the Germans to Mexico, which got decoded by the British. This telegram basically stated that if Mexico attacked the United States, Germany would ensure territories for them when they won the war. This finally caused President Woodrow Wilson to declare war in 1917, and the United States finally joined World War I.