Why US entered WW1

US involvement in WW1: Causes and Consequences

The United States initially intended on remaining entirely neutral in World War 1. We wished to remain neutral in respects to continuing to build our economic trade routes with both the Germans and the British/French. When the British imposed a loose blockade of the German waters in order to slow or stop the amount of supplies the Germans had, the Germans resorted to using their submarines to put a blockade of sorts around the British Isles as well. During this blockade of Britain, the Lusitania is sunk by a submarine and 128 American citizens perish. After the sinking of the Lusitania, Germany removes the submarine blockade of the British Isles, and trade between Britain and the US goes nearly back to normal. The fact that the US were protesting the use of German submarines, and not protesting the British blockade of German ports, gives the impression that Wilson was leaning more toward the side of British and French, rather than keeping a neutral stance anymore. This is believed to be one of two reasons that the US backed British and French forces. The second, and possibly more important reason, is the British blockade of German ports had stopped trade with not only Germany, but any countries within proximity of those waters. The US had to divert that trade to open countries in order to maintain economic stability. Once the allied countries had exhausted all their credits with the US, we opened our private banks to them. We gave them over 3 billion worth of contracts and help. That amount of money could also be considered another reason for backing the allied forces. In response to this US backing of allied forces, Germany resumed its blockade of Britain. Which in turn caused Wilson to sever all diplomatic ties with Germany, and to arm most US merchant vessels in order to combat the German submarines.

References:
Keylor, William R. (2011). The Twentieth-Century World and Beyond. Oxford University Press, Sixth Edition.

References: Keylor, William R. (2011). The Twentieth-Century World and Beyond. Oxford University Press, Sixth Edition.