You didn't list any factors, but there were many.
For instance, the USA entered World War I because Germany had sunk a ship with US passengers, the Lusitania, after an agreement that neither would attack in the sea warzone.
Another factor that caused the USA to enter World War I was the Zimmerman Telegram, Germany sent a coded telegram to Mexico in hopes of getting Mexico to ally with them and turn against the USA.
Hope this helps!