Why did the us join ww1

The sinking of American merchant ships caused the US to join WW1

"now, up until just before the u. s. declared war on april 6th, 1917, the u. s. had desperately tried to stay neutral, but ties to britain, propaganda, the sinking of ships by german u-boats, and a german attempt in the zimmermann note to get mexico to declare war on the u. s. pushed the u. s. to getting involved."

(this is basically what drew america into war.)