Answer:
The United States became involved in World War I for a number of reasons. One of the primary reasons was the sinking of the Lusitania, a British passenger ship, by a German submarine in 1915. This event resulted in the deaths of 128 Americans and enraged the United States, leading to increased tensions between the two countries. Another factor that contributed to the United States entering the war was the interception of the Zimmermann Telegram, in which Germany proposed a military alliance with Mexico against the United States. This event further fueled American anger towards Germany.
As a result of its involvement in World War I, the United States underwent significant changes. One of the most significant changes was the expansion of the federal government's role in the economy and society. The war led to increased government intervention in areas such as labor, agriculture, and finance, which laid the groundwork for the New Deal policies of the 1930s. The war also had a significant impact on the role of women in society. Many women worked in support roles during the war, and this helped to pave the way for women's suffrage and greater gender equality in the years following the war. The war also had a major impact on American foreign policy, as it marked the country's emergence as a world power and led to increased international involvement in the decades that followed.