The 1910s were a decade of great tumult and change in the United States. The decade began at a time of peace and prosperity. America found itself the richest nation in the world, thanks largely to the growth of huge companies that sold goods all over the world. The president, William Howard Taft (1857–1930), had succeeded Theodore Roosevelt (1858–1919) as the leader of the Republican Party, which offered its support to American businesses. Many Americans enjoyed improved living standards, as more people owned cars and used electricity in their homes with every passing year.

Great disruptions soon came in politics, international affairs, and the economy, however. In the presidential elections of 1912, Roosevelt left the Republican Party to become the nominee of the Progressive Party, the first serious challenger to the two-party system in many years. He and Socialist Party candidate Eugene V. Debs (1855–1926) helped steal votes...