Esler, Ellis. World History The Modern Era. Boston, Massachusetts, Upper Saddle River, New Jersey: Pearson Prentice Hall, Copyright 2007.
http://www.thenagain.info/webchron/world/uswwi.html
Bibliografía
Many Americans supported the Allies because of cultural ties. The United States of America shared a cultural history and language with Great Britain and sympathized with France as another democracy.
A big reason that made the Americans join the war was the Zimmermann telegram, which said that if Mexico would help Germany, Germany was going to recover the lost lands of Mexico in USA which were New Mexico, Texas, and Arizona .But Great Britain intercepted the telegram and revealed the Zimmermann telegram to USA and that caused an anti-German feeling to become stronger in the United States of America. So after that, USA declared war on Germany in April 1917.
The Zimmerman Telegraph
The Zimmerman Telegraph
They were about 2 million of Americans that joined the war-weary Allied troops fighting on the Western Front. Just as important to the debt-ridden Allies was American financial aid.(Esler)
One of the causes that made USA think about entering the war was the sinking of Lusitania Ship in May 7, 1815, which killed 120 Americans. Woodrow Wilson had the idea of peace, looking forward to mediate the European conflict, so he made a document named the 14 points. When USA entered the war, armed forces equilibrium broke. There were more weapons, troops and economic pressure in the Allies, at the same time some countries like Cuba, Panama and Brazil entered by the influence of USA, which made World War 1 end quicker.
The Sinking of the Lusitania
“There are many other theories regarding why the US entered into World War I. Some propose that the US was never actually neutral, but had been supporting the British; this thinking gives a different light on the events of submarine warfare with the Germans. The high infiltration of Pro-British propaganda as well as the considerable profits to the hurting economy lead some to believe that it would have been impossible for the US to remain neutral and not engage in the war. Others propose that as German forces crept into the Atlantic and threatened to conquer Britain, the US felt that its defenses and the country's security were threatened, again justifying involvement in the war. In all practicality, it is impossible to pinpoint the entry of the United States to a number of certain events and it was most definitely a combination of many factors.” David W. Koeller