Why did united states get involved in world war one?
The United States entered into World War 1 after the sinking of 7 US Merchant ships by German submarines and the Zimmermann Telegram was intercepted, sent by the German Foreign Minister, that detailed Germany's desire to fund a war by Mexico against the United States to keep the US out of their war.
On April 2, 1917, President Wilson went before a joint session of Congress to request a declaration of war against Germany. Germany's resumption of submarine attacks on passenger and merchant ships in 1917 became the primary motivation behind the decision to enter United States into World War I.