World War I stimulated growth in the U.S. economy. The entrance of women and blacks into the workforce added more than one million to the ranks of working Americans, and factory output increased tremendously. After the war, the boom continued, in part because there was great demand for American goods from war-torn European countries.

The war also affected the demographics of the country. It is estimated that 500,000 southern blacks moved north during the war, most of them settling in cities to work industrial jobs. As urban black populations increased, so did racial strife. In 1917, a white mob in Illinois lit black homes on fire and shot the fleeing inhabitants, killing nearly forty. Weeks later, the NAACP organized a silent march down Fifth Avenue in New York to protest racial violence. The end of the war did not mean the end of racial tension. In 1919, eighty-three blacks were victims of lynching. That year, race riots exploded in twenty-five cities, most notably Chicago, where a thirteen-day riot in July left fifteen whites and twenty-three blacks dead, hundreds injured, and more than a thousand homeless.

After World War I, anti-German hysteria turned into anti-Russian hysteria in response to the Bolshevik revolution of 1917, which brought a communist regime to power. Although fewer than 100,000 Americans were members of the nation’s communist parties, many Americans feared that communist influence went deeper, and had infiltrated the working class, immigrant communities, and labor unions.

In 1919, Attorney General A. Mitchell Palmer assigned J. Edgar Hoover to head a new Intelligence Division to root out subversives. Hoover arrested hundreds of suspected radicals and deported many “undesirable” aliens, especially those of Eastern European background. In 1920, in a coordinated operation, police and federal marshals raided the homes of suspected radicals and the headquarters of radical organizations in thirty-two cities. These Palmer Raids resulted in more than 4,000 arrests, 550 deportations, and uncountable violations of civil rights.

World War I slowed the advance of progressive reform but did not stop it. Progressive forces continued to operate during the war, pressing for further domestic reform. One prominent movement was the drive for prohibition. During the war, prohibition forces pointed to the German names of America’s breweries and argued that German beer would undermine American morality. Prohibitionists therefore presented the Eighteenth Amendment, which prohibited the manufacture, transport, or sale of alcohol, as a war measure. This Amendment was passed in 1917 and ratified in 1919.

The women’s suffrage movement made great strides during the war, largely because of the important role women played on the home front, filling men’s jobs and promoting the war effort. Congress passed the Nineteenth Amendment, which granted women the vote, in 1919, and the states ratified the Amendment in 1920. Despite this major advance, however, women were forced to vacate their jobs and resume their traditional roles when men returned from war. Women would have to wait for advances in social status to catch up to the legal advances they made in 1920.

Many American citizens of widely differing backgrounds refused to support the war. Some were German immigrants, some were members of pacifist religions, and others simply objected to the war on moral and intellectual grounds. Antiwar writings increased as journalists dissected and criticized pro-war reasoning. Intellectuals condemned the war in political magazines, while socialist publications denounced the war as a contest for global market dominance. As the war began, the government did all it could to counter and quiet these criticisms.

Concerned by the antiwar campaigns, Wilson and his advisers worked hard to promote the war. His administration enlisted the help of famous movie stars to urge Americans to aid the war effort and conducted government bond drives to finance the war. In 1917, the federal government established the Committee on Public Information. This committee functioned primarily as a propaganda agency that discredited all critics of the government and set up guidelines for self-censorship. The committee also enlisted the help of artists, journalists, and authors to publicize the war through speeches, posters, articles, and films. These pro-war efforts helped generate and intensify the public’s mistrust and hatred of Germany and the Central Powers.

The patriotic—but often intolerant—sentiments inspired by such propaganda spilled over into public policy as well. The Espionage Act, passed in 1917, enumerated a vague list of anti-war activities warranting fines or imprisonment. The 1918 Sedition Amendment to the Espionage Act provided for punishment of anyone using “disloyal, profane, scurrilous, or abusive language” in regard to the government, flag, or military. Government officials invoked these measures to suppress dissent and justify the arrest of roughly 1,500 people during the war. Eugene Debs, a prominent socialist and five-time presidential candidate, was imprisoned in 1918 for denouncing the government’s aggressive tactics under the Sedition Amendment (he was released in 1921). The Espionage Act was also used to bar a number of periodicals from circulation by mail. The Supreme Court upheld these laws when they were challenged until well after the war had ended, most notably in Schenk v. U.S. (1919), in which the Court ruled that speech could be restricted when free speech presented a “clear and present danger.”