How did American identity change during WWI?

World War One had a major impact on the American identity. Globally, the war established the US as a relevant world power. Prior to 1917 (the year the US entered the war), the US had stuck to a strict isolationist policy, concerning itself mainly with domestic issues and politics. President Woodrow Wilson pushed to diplomatically intervene for peace on several occasions when war began in Europe, but it took three years for American opinion to shift enough for Congress to declare war. American involvement was late but brought about a swifter end to the war in 1918. The true foreign impact, however, came after the war. Though the United States ultimately did not join, Wilson's proposal for a united global organization was realized in the League of Nations (the forerunner to the United Nations). The US, post–WWI, was no longer an isolationist state that concerned itself only with the Western hemisphere.
Within the US, the war drastically changed government, the military, and the lives of ordinary citizens. Previously the government had favored a laissez-faire (limited government intervention in a free market) approach and a small peace-time army. With the beginning of the war in Europe, Wilson began pushing for a policy of preparedness for war at all times. This policy gained steam in 1915 with the sinking of the Lusitania. The government expanded as a result of its need to organize and direct a war effort, building war materials and developing strategy, as well as motivating (with propaganda) the citizens to all take part. This included recruiting workers for the factories, establishing universal military service, and beginning "victory gardens" to increase the food supply. The military was also expanded dramatically so as to be able to fight a massive international war. Most of these expansions remained in place following the end of the war, with preparedness becoming the American standard.