when did the us enter ww1

The United States entered World War I on April 6, 1917, when it formally declared war against Germany. This ended nearly three years of American neutrality since the war began in 1914. The decision followed a series of events, including German unrestricted submarine warfare and the interception of the Zimmermann Telegram, which revealed Germany's proposal to Mexico to regain lost territories if Mexico joined the war against the U.S. President Woodrow Wilson asked Congress for a declaration of war, emphasizing the need to "make the world safe for democracy," and Congress approved the declaration on that date. American troops began arriving in Europe shortly thereafter and played a significant role in the Allied war effort until the war ended in November 1918.