At the end of the 19th century, the industrial might of the United States propelled it into great power status. In the early 20th century, the United States grappled with its new role in the world and the effects of the second Industrial Revolution at home.
The United States entered World War I in 1917, fighting on the side of the Allies. Although the US contribution to the war was small relative to the European powers, the war would go on to affect American life into the 1930s.
The 1920s were both a "roaring" and a turbulent decade for the United States. A thriving interest in all things modern--technology, jazz, social mores--clashed with a cultural backlash against growing multiculturalism and changing values.
In 1929, the US stock market crashed, leading to a worldwide economic depression that persisted throughout the 1930s. In the United States, President Franklin D. Roosevelt attempted to fight the Depression with a series of relief and recovery measures known as the New Deal.