In 1915 the Lusitania was sunk by a German U-boat, killing 128 Americans. In 1916 two munitions factories exploded, which was blamed on German saboteurs. Lastly, in 1917 the Zimmermann Telegram was released to the public and was seen as the last straw by the American public, who now were in full support of war with Germany.
War: 1914-1918 US military involvement: 1917-1918
Financial motives
Eugene V. Debs
The Progressive Era came to an end in 1917, which was the year the United States joined World War I. Woodrow Wilson was president from March 4, 1913 to March 4, 1921, including all of World War I.
US involvement was tremendously helpful to the Triple Entente; it is likely that the outcome of the war would have been different had the US not gotten involved, either a victory by the Central Powers, or at least a stalemate, which would have resulted in a very different peace treaty than the Treaty of Versailles. This would have had huge historical consequences of various sorts.
They got involed in the war because the Japanese bombed pearl harbour.
The (RMS) Lusitania.
1941
they were a allie.
How_did_the_us_involvment_in_World_War_2_escolate
1945
Supplying Allies with weapons
The Japanesse surrender.
Self defense, the US was attacked.
The US is not yet involved in world 11. The next world war should be WWIII so they have a way to go.
December 7th 1941
The US entered World War 2 after the attack on Pearl Harbor. When over 2,400 US lives were lost in a sneak attack on a Sunday morning, there was no stopping US involvement in the war.